A lot of people compare TKO exhausts to Berk but do not realize that Berk is full stainless (except for hangers), while the TKO has aluminized piping. KO Racing (TKO) does offer their exhausts with stainless steel piping, but the price jumps quiet a bit if you go that route.
Aluminized exhausts do last long though, but not as good as aluminum, stainless steel, or titanium exhausts so I would coat it with something to try and make it last longer if you end up getting one.
If you go for TKO 3", go with the 7" mufflers.
As Kaku posted, MR2oc always has great deals on their authorized vendors and group buy sales section, especially for Berk exhausts.
I got my Berk for roughly $550 brand new from one of them!
A 3" exhaust is a 3" exhaust whether new or used, if you get a stainless steel one and make sure it has no dents or anything that bothers you then it's definitely worth saving the $100-200 for a used one OR get a good deal like I did.