user11927: I want to "connect" two Arduinos, without using wires. The range is ~0.2 miles (300 meters). Using Google, I saw too many options.
The idea is to build something like a beacon, so the bandwidth can be small. I want to send 32 or 64 bits/second of data (32 bits for the application + 32 bits for checksum if the module does not guarantee consistency of data). 
The communication between Arduinos is bi-directional, and I'm looking for something cheaper than 50 US dollars per module.
Can I use a serial WiFi module for this, without using a router? Do you recommend a 2.4GHz module? Or a RF module?

user3688: I can highly recommend these cheap little 433Mhz radios.  You can get them on amazon, ebay, etc. and they work pretty well for me. Your distances are a bit longer than my situation but I have to go through several walls.

11927: <p>I want to "connect" two Arduinos, without using wires. The range is ~0.2 miles (300 meters). Using Google, I saw too many options.</p>

<p>The idea is to build something like a beacon, so the bandwidth can be small. I want to send 32 or 64 bits/second of data (32 bits for the application + 32 bits for checksum if the module does not guarantee consistency of data). 
The communication between Arduinos is bi-directional, and I'm looking for something cheaper than 50 US dollars per module.</p>

<p>Can I use a serial WiFi module for this, without using a router? Do you recommend a 2.4GHz module? Or a RF module?</p>
 3688: <p>I can highly recommend <a href="http://smile.amazon.com/gp/product/B00INTI8R2/ref=ox_sc_sfl_title_6" rel="nofollow">these cheap little 433Mhz radios</a>.  You can get them on amazon, ebay, etc. and they work pretty well for me. Your distances are a bit longer than my situation but I have to go through several walls.</p>
