The costs of printing are based on the prices per kg from MakerBot -- if they work, and people pay, continue going with the brand that works? FirstBuild carries some in stock and can order them for us to shave shipping.
Lulzbot also sells it, and it should be of decent quality.
The other manufacturer I used before is MakerGeeks www.makergeeks.com
Just send the requested item URLs & quantity to broken and they can be ordered.