Wait for RS to clearance out speaker grills. Otherwise they're VERY pricey there. Small grills have typically started at $10 a piece.
However when they clearance out stuff, they have good deals. I guess last fall (accd to the newsgroups) they had an near identical match to Midway cocktail table speaker/air hole grills (6x9). They were same size, same style and same metal. Only difference was a textured powerder coating rather than smooth on the outside. Their blowout price? 97 cents!!! (dont worry, they're gone now.. I checked all in my region and are out)

Actually I'd check out thrift stores and garage sales.. You may find some good stuff there. AND if you need speakers, here's a tip.... Look for broken boomboxes where the cassete or CD doesn't work and it is all banged up and has paint splatters/etc... Inside are probably two perfectly good 8 ohm 5-10 watt speakers...perfect for your machine(s). All for the cost of a buck or so.