Ant - the best transmission:
http://www.gforcetransmissions.com/ The GF5R is the 5 speed that you'd be most interested in. Over $5K USD, so it's certainly above the Top Loader, Nash, Richmond, & Jerico pricing.
I spoke with Holinger about their 5 or 6 speed sequential transmissions, and they basically said that they didn't think their trans would last in my car, and that I'd therefore be wasting my money. At $16000, you'd want a more positive answer than that... Mike Long from G-Force is confident that his trans will last behind 1000+hp motors without a problem.