seancfc, I can't think of a set for that price, but one thing to consider is,
Although it "is" nice to have a set of near field monitors (which is what I think of when i hear the term studio monitors) mainly because of their flat response for mixing and the fact that they don't usually produce back waves /reflections off of wall, ...it's not a need-or-die kind of thing.
If you get a set of cheap speakers (even at a place like Best buy for example) as long as they sound ok, and you don't notice any major frequency dips, (that is instruments in the music that don't stand out like they should) you can still have success mixing down. It's more about getting use to a set of speakers, and testing your music on multiple speakers and making adjustments to the settings you've originally made.
For example. If you have a cheap set of speakers that are naturally on the bright side, you might have a tendency to set your high frequency's down low because they sound too bright, in this case now your mix sounds dull on all the other speakers you test them on. This might indicate that you need to make the mix brighter on the original speakers (even though they sound brighter than you would like) in order to get them to sound good on speakers that might not be as bright. Obviously I'm generalizing this example, but in the example of your speakers being on the bright side, you would still need to narrow down "what" frequency in the low-high, Mid-high, and very high as the root cause to be adjusted. I think the majority of times, the advantage of near field monitors can be substituted with standard speakers by being familiar with how a set of speakers sounds as you're mixing, and then making changes by comparing the results you hear on other reference speakers.
side note: Having some sound padding, like a carpeted wall behind the speakers might help dissipate secondary waves from bouncing back at you and causing phase cancellation issues. That is "one" of the advantages of near field speakers, but you can use something on the wall when using none studio monitors to kind of simulate the same mechanism.
