Here's a quick overview on the size of your tires. A 215/55/R16 is broken down like so...
215 is the width of the tire in millimeter, so it's 21.5 centimeters. The 55 is referred to as the sidewall aspect ratio. Basically, you take the width (215) and multiply it times 55% which gives you the sidewall height.
Anyways, yes, you can use a different size tire, BUT no it's not recommended. The tire size you are using now, is a "best" fit for the rim you have. You could go wider/narrower, taller, lower, but then things start changing. If you change the sidewall height, you end up with a speedometer and odometer that don't read correctly anymore.
As for a suggestion... I personally like Bridgestones, but if you're trying to keep things low cost, I'd recommend the Nexens. Here's an Ebay link
http://cgi.ebay.com/ebaymotors...wItem
I haven't personally used them, but I've heard good things about them. You can do a search on the site and there should be a few threads about them.
You can buy them on ebay for about $300 including shipping and have them installed somewhere in your area for $10-$20/tire putting you around the $350-$380 range.
Also, check the independent tire dealers. They're usually less expensive and easier to negotiate with. The only benefit in going with a big dealer is warranty.