+1 for the Behringer Truths. For the price they are excellent and are not nearly as "colored" as KRK's. The KRK RP line kind of sucks in my opinion. I owned the RP-8's and although they are great for *listening* to music, they aren't very faithful for mixing / mastering at home. The low end is too exaggerated, the mids are a lacking presence and definition, and the highs can be fatiguing after a while. Bear in mind, this opinion is based upon critical listening for mixing purposes, not casual "just listening to music" purposes. The RP-5's are also not very powerful bass-wise, so even if you did want to go the KRK route, I would suggest going up to the RP-8's. They can shake the house. In my opinion, the best budget monitor choice right now is the Yamaha HS80m. They are unforgiving and do not "sound good," meaning they will not flatter your music by making it sound better than it actually is. They are brutally honest, IMO. This is good because it forces you to record better, mix better, etc. They're only $299 apiece, which I feel is a real bargain. You can get the matching sub for another $300 and have a fantastic monitor setup for less than a grand.
So in short, the KRK's are great if you just want some good monitors to listen to music... but if you want something that will translate well to other sources, whether that be headphones, car stereos, home stereos, ipods, etc... get something less colorful. The Behringer Truths mentioned previously are good for the price but I'd spend a little more and get the HS80m's... skip over the HS50's...
Of course, if the acoustics in your room are crap, it really doesn't matter what monitors you buy.
---------- Post added at 06:06 PM ---------- Previous post was at 06:01 PM ----------
One other thing... the best-sounding KRK monitors IMHO are the KRK VXT6's. They're quite nice but I dig the Yamaha HS80m's way too much. The main thing to remember is that you will hardly ever find a general consensus view when it comes to monitors because it's all very subjective. It is totally possible to make a great-sounding mix with KRK monitors but you have to have them set up correctly, positioned correctly, have your room treated (if possible), and also learn to work around their coloration.
MPC 1000 w/ JJOS - Korg ESX - Korg EA-1 - Ensoniq EPS 16+ - Waldorf MicroQ - Roland Alpha Juno 2 - Yamaha TX81z - Mackie CR1604 - random rackmount and pedal effects