I know I'm going to get flamed for this, but, do not buy a Serpa holster. There are many reasons why this holster is not a good one, but I'll save that for another time.
If you want a level 2 holster, this one is far better:
Safariland(R) Model 6378 ALS(R) Paddle Holster|The SAFARILAND Group
Friend I hear you and we all want to save a few dollars. However, the holster is an area we shouldn't skimp on. You might only carry when on the ATV, but if you're out for 6 hours, you might wish you had a better one. We only care about comfort when we're uncomfortable. Better to be a little uncomfortable in the pocket book for a moment than to have an uncomfortable holster for hours one day.