HU from USA, will it work?

I have been thinking of getting a new headunit for a while now. I've been looking a the single DIN Sat Nav/DVD type, the ones with the fold out screen and touch screen controls. At the moment the better ones of this sort all seem to retail at around the £1000 mark!
Early next year I am of to Florida competing and was thinking of picking one up whilst I'm out there, but the big question is will it work in my car when I get back and will accessories bought over here work with it or will I have to get everything I want whilst I'm there?
Sorry if this has been covered before, I have done a search but so far drawn a blank.
Cheers All

Cheers pal, looks like I'm gonna need a bit more spending money. I've thought about the tv tuner kits that are available for for these, will one form the states work ok or will I have to get one when I'm back home? And will a UK tv tuner work on a USA headunit?