Just wondering how many headsets you can get.

The only thing i know about them is that they are wireless, the user can control the volume to his/her liking.

How many headphones can you hook up to 1 base?

Can I buy 5 wireless headphones and hook them up to 1 tv ?

You should be able to buy as many as you want. The base station is like a radio station, it just broadcasts to the headphones.

thank you.

now, what companies should i look into?

i would say my budget is $500

I'd suggest looking around here:
http://www.headphone.com/products/headphones/wireless/

The Sennheiser RS 65/HDR 65 is supposed to be good, but might be a bit pricy for you depending on how many headphone sets you want.