Just as a thought, I bought a hole cutter that's designed (I think) for a drill-press. It's basically a drill bit with an arm that connects to an adjustable metal cutter (so you can change the radius of the hole. IIRC, the bit cost me about $8.
Get ready for some ascii art:
(bit)
||
|| (arm)
||__________||__
||---------------||---
|| ||
|| ||
\/ |/
(cutter)
Anyway, I bought this instead of a holesaw. I didn't see the sense in paying $25 for something I'd use once either. Instead, I paid about $8 for something I used once.
Anyway, if you'd like to try it, I'm sure it'd cost less than shipping someone else's holesaw back and forth.
As a side note, I believe I used my drill in reverse when using this, but in retrospect, it's probably not necessary. Just use your drill at a semi-slow speed and all should be well.
Edit: made ascii art a little clearer... (maybe?)