Gerogie: I hope you're not serious about re-using a rig 50 times, I don't care how well it seems to hold up, that's just insane. I'll use a rig 3 or 4 times (all in one "session," since that's how many hits it takes to go through all the meds). But even after "only" 4 hits, when I open a fresh one I can totally feel the difference, it just goes in like butter!
It doesn't matter what rig you use, it's safer and helps minimize track marks to use a new needle every time.
Sure, its possible to reuse and not have issues, but it will always be better with new ones. Always.
And seriously, no whining about how there is no exchange near you or the local pharmacy won't sell them... You can buy a box of 100 online for a few bucks, so there is really no excuse to use a needle over and over again until it becomes a fucking ball point pen!