My advice is to buy the best speaker you can afford without regard to whether you'll need a subwoofer. Subs are nice (I have two in my system), but they can't make up for a speaker that lacks good mid-range qualities. Further, even good subs are much more effective when paired with main speakers that have good extension down to around 60 Hz.
You might have to plan your purchases incrementally (monitors now, subs at a later time), but in the long run you will be much more satisfied if you get the best main speakers your budget will allow, and worry about the subs later.
Having said all that, I think you should give the Rainmakers serious consideration. However, in their general price range there are some other very good speakers that you may like, and that deserve an audition: B&W 602.5 S3; Bohlender-Graebner Radia Z; Magnepan MG12/QR; ProAc Tablette Reference 8. If you are willing to buy used speakers, you can also get a pair of Vandersteen 2Ce's, which would be an excellent starting point (and which will mate very well with a subwoofer at some future point.)