To buy a book- Walk into a store, select book, walk up to the cash register and pay for it.

To buy a Vegetable- Walk into grocery store, cruise back to the fresh produce, select vegetable, walk to cash register and pay for it.

To buy a Glock- Walk into a gun store, ask the sales staff to look at a Glock, decide you want the Glock,  pull out wallet, hand the sales staff your drivers license, fill out ATF form 4473 (if you lie on it, it's a felony), sales staff calls NICS to see if your record is clean (if not, no gun for you), receive a "GO" from the NICS operator, sales staff rings up the purchase.

Which one is easiest..? I'll let you decide.