These modules are all pretty expensive - is there anything cheaper?
heh. you remind me of the old network engineering joke:
"""you can have only 2 of the following 3 in any network: Reliable, Fast & Cheap."""
if you want long range and easy to use then you will have to pay a lot.
if you don't mind sacrificing range then the price will come down.
likewise if you want to build the module yourself from tiny surface mount components and laser etch tuning circuits then the price of the components will come down. (but obviously the price of the lab required goes waaay up,)
if you want "easy to use" at the range you are looking at then the XBee modules are some of the best i've seen.
if you need lower latency or don't mind putting a lot of work in there are some CYRF6936 based modules out there that do what you are asking but the development time will be much longer.
search DigiKey for all it's RF modules.
the toughest thing is working out what range a particular transmit and receive power will give. i've only reserched this on 2.4GHz modules so can't comment on other bands but here's some numbers ***for 2.4GHz only*** to get you started:
to get the range you are talking about at 2.4GHz from a DigiKey search you will need a Transmit Power of at least +8dBm or more
and a Receive Sensitivity of under -90dBm.
obviously a module with a lower sensitivity will not need such a high transmit power at the other end.
modules with between 100dBm and 130dBmdifference between Transmit Power and Receive Sensitivity will be worth investigating.
to add to the confusion power levels are measured in dBm (DeciBels per Meter) which have a logarithmic scale so although i'm putting numbers on the difference between TX and RX power, they don't actually make any sense.
the XBee-pro: range 1mile. Power output: +17dBm. Receiver sensitivity: -102 dBm.
the UGWJ 4US module i am using: range over 1mile. Transmit Power: +23dBm. Receive Sensitivity: -97dBm.
you might just get lucky and find a long range module on DigiKey at a reasonable price. if there is one it will probably operate on a low frequency and so relatively low bandwidth.
i'm guessing this is for a RC UAV right?
hmm, now i think about it, i should have mentioned, Transmit power can also be measured in mW (mili Watts) so you will also need to work out the mW to dBm conversion for transmit powers.