i just bought an 18 piece holesaw set at a store called Harbor Freight Tools. it was only $4.99. i'm sure it isn't of the greatest quality, but for doing a few holes in a control panel it should be fine. it seems as if they have stores all over the country, so if there is one in your area, you may want to check it out.
Buy all of your tools at Harbor Freight. Probably 90% of the tools I own have come from there, and I own a lot!
As I tell all my friends and co-workers, stuff at Harbor Freight is occasionally *so* cheap, I can't afford *not* to buy it!
I have an 18-volt VSR cordless drill from them that I've had for over 10 years now. It gets used every weekend. Not to mention I've used it to build a house, including drilling all the holes for wires and plumbing. I've really used it hard. Even briefly dipped it in salt water working on my dock.
I paid a whopping $60 for it.....the equivalent DeWalt model (of which mine is an obvious Asian copy) was $199.
I've also found you can buy some heavier tools from Harbor Freight for what it would cost you to rent one for an afternoon anywhere else.