Thats it! I'm not sure how many levels you can use before the system starts adding errors, but I think 4 would be a good start, and for a 'DAC' a simple 'R2R' ladder would do the trick - Again, simple and cheap! The ADC at the receiver would probably be harder, and the more resolution the more room for error you'll have. This setup should push most of the complexity into the FPGA, which can be a good thing, or a bad thing, however, there is plenty of info on the net, since 802.11 uses a similar sort of thing, although, with QPSK.
To be honest, I haven't got mine working yet, since they require 0.05" pitch connectors which are tiny and very hard to aquire here in the UK, but thats my fault for buying the ultra small modules that run on 5v and low current.
Most of the modules are probably about $30US (£20UK right here) for a Tx/Rx pair. And nearly all have an antenna connector 'built-in' and a nice convenient 0.1" standard header for power and singals. Most seem to run off 12V. Also they have a built in microcontroller, so channel selection will simple need a 4-way switch. The 2.4Ghz spectrum is crowded, and because these are analogue, no interference-protection is provided (DSSS, FHSS). So, I imagine they're not that great for analogue video, where noise in the channel would directly effect the video, digital should be far more robust.
Sorry to keep going on, but I'm gonna use these for digtal audio, because the S/PDIF signal is very similar to composite video (1v p-p 75 ohm etc...) so if you want to find a 'simple' interface, search google for 'ttl to S/PDIF" (or visa-vesa). These require a couple of inverter gates and a couple of passives, and according to some operate up to 6MB/s (note this is 2 signal levels and no pulse shaping, and is not 'true bit-rate', but the symbol rate, due to over-heads in your packets).
With this setup it should give you an idea of what speed it can operate at, and if you buy them and decide not to use them for this, you will have a simple wireless A/V system to watch DVDs elsewhere in your house
I'm don't know where you live, so I can't comment on availability/restrictions. heres a good place to strat though:
**broken link removed**
Hope this helps, google will have loads of matches for "2.4Ghz A/V module"
BuriedCode