I presume you are looking on PistonHeads? That seems to be the place as there is such a strong TVR presence on the whole site. I would just be wary of an early (2003/4) car that hasn't had an engine rebuild as it almost certainly will need one at some time.
I promise you, it will be the most rewarding car you'll ever buy as long as you don't listen to the pub bar bores (or Top Gear for that matter) and you go into ownership with your eyes open.
TVR owners are a really friendly and supportive bunch so if you need any guidance or help to select a car just ask. Someone will jump in their car or get on the phone and offer to get stuck in.
Email me if you need anything.
E92 325i M Sport, Crimson Red, Alcantara Trim, 19" Cades Tyrus Staggered Deep Dish Alloys
TVR T350C 4.0ltr Red Rose Spec, Space Green