If you go to "shop online" they have all their prices listed without having to submit anything. This one shows the 8x12 I ordered,
Freestanding Economy Pergola
I paid extra to get the 6"oc slat spacing rather than the default 9", I probably should have gone even closer. And I think I'd get the 10' wide next time, the 8' wide really only gets you 7' wide of shade because the slats start 6" in from the ends.
This page has the economy and deluxe versions in freestanding and wall mounted. Click from there and you'll see the prices of each type.
Aluminum Pergolas
Mine was just under 2.5k, comparing to wood we'd need to nail down a few specifics.
Just straight PT posts and 2x's, carriage bolted together I think you could get it done for 1/4 of that pretty easily. I was aiming for something a little nicer than that, that would hopefully last a little longer.
If you're talking about good quality trim boards and painted, you'd be lucky to make one for half that I think, bought as a kit or completed unit it could be more than I paid.
If I had seen a vinyl kit anything like that one I probably would have went with that. We don't have a costco nearby, so didn't think to look there. The box store kits all had main beams that bolt together in sections. They looked hokey, cost a fair bit and I'm not convinced they'd last very long. They'd probably be OK, really, but I guess I just didn't like them.
I was pricing fiberglass porch posts and such leading up to this, trying to think up ways sandwich vinyl trim boards around metal pieces. Doing that I certainly could have spent this much easy to come up with something that doesn't look as nice, been a lot more work, and kept me busy all summer.
I was debating getting some logs (white oak or cedar, maybe) from a local tree service and making a log structure. Or a combination of welded metal trusses (I was thinking of getting some shapes plasma cut to make up the web of the trusses) and either log legs or even something like concrete with a structural metal core, poured on its side then bolted upright once cured. But all of those options would have required a lot more lead time, and I was really hoping for something that get me closer to done sooner, so this really fit the bill.