Does anyone know where i can get the proper pvc pond liner from. Has anyone tried standard tarp pvc and had it sewed?

If your in Bangkok Chatuchak fish market has everything you'll need, we have a small pond (rectangle) and I used the normal black plastic you see around trebled it and folded the corners and not had any problems.

If you were building a larger pond there are several firms that have the product and the installation teams in Thailand. GSE is one company with an office in Bangkok and staff who speak English:

http://www.gseworld.com/Applications/Agriculture-and-Aquaculture/

You can try this company www.kasetplus.com and plastickaset.com they also have a page on facebook.