If you do a forum subject search for 'fuel tank', there are several old threads that will help.
There is a fabricator in Florida that a lot of guys have used named Tony Perez (
http://www.sunrisemarinetanks.com) I have talked to him and he has excellent prices. There is also a source for poly tanks in Florida. From what I've seen, even with shipping, these guys are cheaper than the local Houston fabricators who are quoting $13/gallon.
Speaking of shipping, if anyone needs freight quotes, I have a guy who is excellent. He has saved me a ton of money on trucking. I shipped my new Suzuki motor from S. Florida to Houston for under $150.