The big/main name I see are Bare, DUI, USIA, aqualung, Apollo.
Considerations like neoprene vs shell, boots vs rock boots, latex or neoprene wrist/neck seals
I've had good luck finding suits for friends on Craigslist in the $200-$300 range and I think that's pretty solid deal.
But most importantly I think is how the suit fits you personally.
Just my 2 psi, I'm sure you'll head 100 answers from 100 different people.
"Whoa! Big ol' blue's one serious place, dude." - Crush the sea turtle