I like Amazon OK, you might also check
www.discounttiredirect.com. That's where I got my Maxxis in March 2011 and at that time they had the best price. I corresponded with a service agent by email with a couple questions and had a good experience with them. I had wanted "E" load range but they did not have those at that time so I got the "D" load range. I had the tires mounted to the rims, with metal valve stems, by a local shop and put them on the TM myself. I probably have about 9000 miles on them since purchase, no problems so far.
The ST225/75R-15D1 113 B Maxxis tires were $108. each including shipping, at that time.