has any one had to replace the drive belt on their bike, and if so how much was the belt? i have 500 miles on my bike and i just checked the spec book on the belt slack and found it to be out of specs.

 

The drive belts seem to be around $70 from several places here in Portland, Oregon.
I've had mine for 2 1/2 years and have way more than 500 miles on it and my belt is still fine. You may have a pre-mature wear problem.
The belt is easy to replace once you get past all the platic body parts.