There are two ways you can go about accomplishing your goal, from my perspective. One solution is to get two nice speakers now and a cheap, temporary stereo receiver or amplifier, and the other is to get a nice AVR and just a couple inexpensive but decent speakers to start out with- and those inexpensive speakers can go to the rear channels when you can afford more substantial fronts.
For solution one, look on craigslist or ebay for a receiver or amp, you ought to get a pretty decent one for 100 to 150, then go with some speakers around the $600 range. MMGs would be nice, also look at Ascend Acoustics CMT340's, Aperion 6Bs, EMPtek E5Ti or E55Ti, or Infinity Primus p362s. Of course, you should audition what you can locally, also look through audiogon.com to see what can be had there.
For the second option, I would go with a five to six hundred dollar receiver, like say a pioneer VSX-1129, Onkyo TX-SR708, Yamaha VX667, and correspondingly priced lines from Marantz, Denon, and Harman/Kardon. Then I would get some inexpensive but good speakers, something like Infinity Primus P152s, or P162s, or Behringer 2030ps. Also check out these TCA WAFs
, great deal right there. Also check Craigslist, Audiogon, and ebay to see if there any good used deals.