Are you looking to just record everything separately or actually record a mix as well?
If you want to do both, you could go with the 744T (wonderful device!) and a mixer like the PSC Promix 6, which has not only 2 sets of XLR outputs (you can go to recorder and camera, or two camera, etc...), but also has Direct Outputs on each channel. It would allow you to do a mono mix and Isos for up to 3 channels (when paired with the 744T). More if you get a fancier recorder (ie - if you got an 8 channel Deva, SD, Nagra, or Tascam (another) field recorder, you could do a stereo mix + 6 Iso channels).
If you want to just plug everything in and not mix, I'd just go with the 744T. Keep in mind that there are only 2 preamps on it. You'll need to go line in to the other two inputs (using TA3-F adapters). This works fine with most wireless, but if you have a mic level, you'll have to get a pre in front of it (mixer, mixpre, etc...)
If you want an all-in-one solution, you can go with the 788T (awesome), or the Zaxcom Nomad (also awesome). Both can multitrack as well as mix within the unit.
Nice thing about the 788T is that you can get two different control surfaces for it, as well as the CL-x accessories.
Nice thing about the Nomad is that it already has a decent control surface on the front panel, and it's dirt cheap for what you're getting!
As far as where to buy?
I buy most of my stuff from B&H or Coffey Sound. There is also TAI, Markertek and Trew. These are all in the USA though. Not sure about overseas.
Ebay works well too :-)
Happy hunting! Let me know if I can clarify or expand on anything for you.