You can get a set of new ones for $600, which is the route I went. The intake manifold will also be an additional expense-Edelbrock makes a good one. If you can check out a set of heads before you buy, then used would be a good bet. I can tell you a bit about my experience.
I also used the newer style Vortec reusable manifold gaskets-no worries about sealing and they're reusable. Vortec heads can't accept a whole lot of cam lift (I think around .475 is about it) without machining, so keep that in mind. I was using a Comp 4x4 cam, so it's biased more for low end torque and not an issue. I went ahead and got the Comp roller tip rockers in 1.52 ratio for a touch extra lift. If you do change rockers, make sure you get self-aligning ones. The install went smoothly-other than needing the new manifold it's a direct bolt-on. I found that for the headers I was running, the multi-piece GM stock exhaust gaskets worked the best (Vortecs have a slightly different exhaust port shape, but will accept SBC exhaust manifolds). As always, get a decent set of head gaskets (Fel-Pro blue works just fine for daily driver applications) and a new set of head bolts.
Performance-This will obviously vary depending on your setup, but I was pleased with the result. Truck feels significantly stronger off the line, and barely needs any pedal moving around town. On the highway, it requires less gas to maintain speed on level ground or up an incline. It's by no means a high-rpm screamer, but it was never set up to be. The Vortec heads produce most of their gains down low. I'd say if you can get them for the right price they're ideal for a daily driver. If you're planning on significant modifications you'd probably be better off with aftermarket heads. If you want something reliable with a bit of extra performance then the bang for the buck is hard to beat without going to an LS platform.
