I am wondering what should I use for my in dash screen I want at least 7" and it needs to fold out, touch screen would be prefreered but not nessicary, im going to link this to my xbox which will be running in car. it also needs to be fold out.

There are HEEEEAPS of the 7" retractable screens on eBay, but they don't have touch screen functionality (what do you want that for?).

If you want touchscreen (for Car PC or whatever) you need to stepup to a Lilliput or something, which cost quite a bit more.

I am using it for my xbox, so i think i might only need the screen.

As I think i can control xbox linux using the controller (havent tried yet)

And this will contain all my videos etc.

Yeah there are a heap of these on the market, the best thing to do is go in to some shops and have a look at them. When it comes to screens, you really do get what you pay for!
I wouldn't recommend the rubbish on ebay, check out your local car audio specialist.

How much am i looking at for a genuine one?

pfft go cheapo... customise it into your dash. genuine are pretty exxy for what they are imo

At least $800. And 7" is pretty much as large as they go.

a nice lilliput 7" fold out touch can be had for around $500 on ebay, maybe cheaper if you wait for the right one to pop up, they are tops screens