Compared to the price you paid for the rotary, you can't find decent pads that are still "cheap".
Edge 2000 are highly recommended, but more expensive up front (until you consider that they are double sided, so effectively two pads in each).
Many folks seem to like
Lake Country curved like these:
http://www.autogeek.net/curvededge.html
You'll probably want to get a good flexible backing plate like:
http://www.autogeek.net/6-inch-rotary-plate.html
But if you have to pop the $20 on a backing plate anyhow, maybe you'd rather just go with the Edge 2000 pads and adapter?
http://www.autogeek.net/edge20008pads.html
(or they have Edge 2000 waffle pads if you prefer)
If you're going super cheap, I'm guessing you might be able to get away with only buying a green and blue pad. That's what I bought - the green and blue Edge 2000 waffle's (haven't used them yet). That's about $38 for the Edge pads versus about $22 for
LC pads, so you'd have to figure out if the $16 difference is worth it to you. For me it was an easy choice (and I'm a tried and true cheapskate

).