I use "santoprene" tubing from mcmaster-carr, it's the same as the "thermoplastic" high-temp tubing sold at northern brewer. Eventually I'll be switching over to silicone tubing which is even better for high temps and flexibility.
It's not cheap but is flexible and holds it's shape at temp. I have compared pricing for it at other places and it looks as if the b# prices is pretty fair at $2.10 a foot. Plan on a large order to take advantage of their free shipping and order more than you tyhink you'll need for just in case. I ordered 50 foot initially and have yet to have the need to replace any lines.
I use Silicon tubing for the high temps. It is about $2.25/ft. but you only need about 7 ft and you are all set. It is nicer to work with than the clear tubing. Better insulated, and it is actualls NSF rated for the temperatures you encounter for brewing. Some tubing is simply NOT RATED for these temperatures. That does not mean it is unsafe, just that it is never tested...
But then again I am a compliance engineer. Maybe I'm just a sissy.