The Costco frames are much heaver tubing.Harbor Freight $149ea. plus you can get or buy on eBay a 20% off coupon, makes them $120 ea.
http://www.harborfreight.com/10-ft-x-20-ft-portable-car-canopy-69034-8696.html
That's the same guy's treeman....that's the guy's I bought from...I have this link saved, same thing, but more stuff.
http://www.costlesstarps.org/Greenhouse_Kits.php
TMB-
These dude's ripped you off JJ.
Hahahaha I forgot that pic jj and the bricks holding the carport up....pretty sure that was one of the first pics I ever seen on riu when I first found it.
Love it...!!!