You get an Oyster card from the machine at a tube station.
As for the refund Oyster Card Refunds
The £5 deposit you pay for an Oyster card isrefundable along with any pre-pay (
Pay as you go) money left on thecard.
Before you claim a refund, it’s worth bearing in mind that if you’veused your Oyster card on a Pay as you go basis and it’s not loadedwith a weekly Travelcard or bus pass
then it’s transferable.
And themoney doesn’t expire so you can give it to a friend, relative oranyone else to use.
If you don’t know anyone who might want to use an Oyster or you don’tplan to return to London, you can get back your unused money.
Where to get a refund in London
Your £5 deposit and up to £10 of Pay as you go money can be refundedat any London Underground (tube) station ticket machine
If you have more than £10 of Pay as you go money refunds are availableat TfL Visitor Centres.
If you have an online account with TfL, refunds are available online.
Once you get your Pay as you go credit and deposit refunded you willno longer be able to use the Oyster card.
How to get a refund after leaving London
If you can’t visit an underground station before you leave, send yourOyster card and photocopied proof of name and address to TfL: Oyster Refunds 4th Floor 14
Pier Walk
North Greenwich London SE10 0ES
Refunds by post will be sent by cheque (£) or by bank transfer to yourbank accounts (UK addresses only).
If you have any questions, contact TfL Customer Services on 0343 2221234 (open daily 8am–8pm).
Last updated: 5 January 2016 Source
travel.stackexchange.com/users/19359/Ulkoma
Note that there is a specific option for a Visitor Oyster card .
This is the same as a normal Oyster, but you pay a small fee (£3) to buy it instead of a deposit (£5) on a regular Oyster.
One big advantage of a visitor Oyster is that 11-15
yr olds can get the child discount without needing a Zip photocard.
According to https://visitorshop.tfl.gov.uk/help/visitor-oyster-card/ : Children aged 11 to 15 can also use a Visitor Oyster card and benefit of the Young Visitor discount – this can be added by a member of the staff at most Tube stations in London and offer children 11 to 15 years old half adult pay as you go rate for up to 14 days.
travel.stackexchange.com/users/47079/mike_dowler
In January 2016, you could not get a refund within 48 hours.
During our visit to London on the 1st of January 2016, we found out you can not get a refund for your Oyster card through a machine at the station within 48 hours of buying it.
This was confirmed by a Transport for London employee, but I could not find this requirement in writing, now or then.
travel.stackexchange.com/users/47090/LondonVisitor
On the site of the London Travel card you find the prices of the travel cards and the Oystercard caps for the same zones.
Travelcard Prices(these are subject to change and prices are controlled by TFL)
Select type Day
Anytime Price Off Peak Day Price Adult Zones 1-2 £12.00 £12.00 Adult Zones 1-4 £12.00 £12.00 Adult Zones 1-6 £17.00 £12.00 Oyster Card Capped Prices Select type Day
Anytime Price Off Peak Day Price Adult Zones 1-2 £6.40 £6.40 Adult Zones 1-4 £9.20 £9.20 Adult Zones 1-6 £11.70 £11.70
So yes, you are right to want an Oystercard for two days use of a travel card, even if you do not get the deposit refunded.
You pay a £5 refundable deposit to get an Oyster card.
You can get an Oyster card at any tube station as well as at several other locations.
This site explains the refund.
If you don't have a contactless and Oyster account, you may be able to get a refund from a Tube station ticket machine if your card has: No more than £10 pay as you go credit
No valid season ticket
travel.stackexchange.com/users/27650/Willeke
It might be worth noting that these days any contactless credit or debit card can be used in place of an Oystercard.
You will be charged the same as if it were an Oystercard.
However, teenagers may not yet have their own bank account and debit card, and not all cards are contactless.
If you have multiple cards make very sure that you choose one and only one card to travel with.
Otherwise you may be charged two penalty fares for touching in with one card and out with a different one!
travel.stackexchange.com/users/47097/Nigel
If you are eligible for any concessionary discount (child, railcard, &c.), DO NOT use contactless, since you will be charged the full fare.
Instead, always obtain an Oyster card and register your entitlement to a discount at a ticket office (National Rail stations in London can usually do this).
travel.stackexchange.com/users/47108/anon
You can get an even cheaper version of the Oyster Card if you're buying it online before arriving in London.
Check this guide (to airport transport from Stansted)
where there's some info about the online version of the oyster card: http://londontravelhacks.com/transport-stansted-airport-london/
travel.stackexchange.com/users/57194/Chris
A group of 4 teenage girls will visit London for two days and want to use a travel card for both days. But a paper travel card is £12 per day and the cap on an Oyster card is about £6.50 for the day.Only one of the girls has a contactless bank card.  Now is the question, where can you buy such an Oyster card and how do you get your deposit and left over money back after the short visit?
Where to buy an Oyster card and where to get the refund after a short time of use
travel.stackexchange.com
<public-transport><tfl><oyster-card>
travel.stackexchange.com/questions/72981
travel.stackexchange.com/users/27650/Willeke
You can get an Oyster card from any tube station or several other locations, but you can now also use any contactless credit or debit card. Oyster cards can also be bought cheaper online. Refunds are not available within 48 hours of purchase, but following this your £5 deposit and up to £10 of Pay as you go money can be refunded at tube stations, and more than this at TfL Visitor Centres. After refunding, you will not be able to use your Oyster card. Oyester cards can be bought at ticket machines in underground stations. Alternatively, you can use your contactless credit or debit card to pay your fare. A tourist version of the Oyster card can be bought online before arriving in London. To get a refund, you need to go to the ticket machines in underground stations for small amounts or TfL Visitor Centres for amount over 10 pounds. Once you have your refund, the card is no longer valid.
Oyster cards can be bought from several locations and there is a cheaper version available online for tourists. Contactless credit or debit cards can be used in the same way as Oyster cards. Refunds of small amounts are available in ticket machines and amounts over 10 pounds are available at the TfL Visitor Centres. Refunds are not available within 48 hours of buying the card. Once you have received the refund the card can no longer be used 