I purchased the window tracks and circle vents from Outwater Plastics. Their website is: https://www.outwater.com. The window tracks are only $0.89 per foot, which includes the top and bottom tracks both. They are very reasonably priced, but this company requires a $25.00 minimum order...
By the way, if any of you guys ever decide to use these plastic window tracks, I researched the hell out of just about every kind of adhesive, glue and double-faced tape known to man and decided not to use any of them for securing the window tracks to the window frames. Instead, I used panel board nails on the bottom tracks and #6 3/4" multi-purpose construction screws on the top tracks. I didn't pre-drill any of the holes and I used a punch to carefully hammer the panel board nails all the way down in the bottom tracks. This worked out very well and I am very happy with my decision to secure them this way instead of using glues or adhesives...
I bet you could sell a couple of the cages you have now on Craigslist or reptile show. Then start over with PVC. I also think in this area you could make a few bucks building these cages.
I am about 45mins north of Pittsburgh. Just look around at the prices for the size cages you just built. Just keep the operation small and custom. Have it just for pick up etc.
Just my opinion that with heavy large snake in PVC I think bonding and screwing is a good idea. TGR even puts a cuts out a center divider in the center of the large 6ft cages for more strength. Interesting design that I seen and liked.
Anyway very nice looking set ups.