The standard response around here is: don't buy anything less than a Sennheiser G3 (used to be G2, but they discontinued those ), and save a few more bucks to replace the stock mic with at least a Countryman EMW.
New, this is probably outside your budget if you factor in the EMW; if you look to buy used, avoid "Block C" G2 systems (anything with a frequency range in the 700MHz area).
I'll have to second that suggestion because anything else is going to total crap. Don't use the stock mics either, they suck. So you're looking actually closer to 750. You can always ebay the unit right after if you're not planning on keeping it.