How far away is the nearest running store? If you just can't get to one that will fit you properly try runningwarehouse.com. They have some online tools and will even let you upload a video of you running for a gait annalysis. I have not used them for that (I have 4 running stores in my area) but their prices look good.

Based on what you said you most likely need a motion control shoe and the Supernova Control should work well for you.  I'm not sure what's causing the blisters.  I've had that problem but only at marathon distances.  Maybe your foot is sliding around a little.  There are various lacing techniques that may help> http://www.runnersworld.com/article/0,7120,s6-238-267--12334-0,00.html and http://www.runnersworld.com/article/0,7120,s6-240---858-0,00.html   Try the Runner's World Running Shoe Finder to get an idea of what shoes are out there. http://www.runnersworld.com/cda/shoelabshoefinder/1,,s6-240-325-329-0-0-0-0-0,00.html  Put in Motion-control for the shoe type.  The problem is getting to try them for fit before you buy them. That's where a good running store is worth it's weight in gold-plated shoes.  For size, remember there should be a thumbnail width between the longest toe and the front of the shoe.

I would find the best store thats closest (within reason, of course) and go there.

You ARE talking about the shoes that will help you  on your journey to greatness...

I have to travel about an hour to go to a shoe store (get2fit) that ACTUALLY knows what their talking about. They know me by now, and I don't mind the extra $ / time it takes, because I know it's the smart idea...