Prefer to use powered monitors for PC setups since all you need are just the right splitters and cables to go from the 3.5mm PC output to RCA or XLR. I have the Emotiva Airmotiv 5 which are powered at 100 watts each. I have them, a 30" monitor, and two small form factor computers on a 30" x 60" office desk. They are above your budget st $450 though.
Since you already have a receiver then you can just look at some decent passive speakers. I like Definitive Technology and use those in my main room. The older Studio Monitor series are very good neutral speakers and Newegg often has these on sale. The SM 350 are currently $150 and are rated at 20 to 200 watts each.
Denon AVR X7200WA, Emotiva XPR-5, Emotiva XPA-7, Sony XBR 75" 850C, Oppo BDP-103D, Roku 4.
DefTech BP7000SC (L/R), CLR3000 (C), SM55 (FH), UIW BPZ/A (SB), UIW 75 (TM).
JBL L7 (Sur), EoSone RSR 350 (RH).
PC 2.1 setup. Emotiva Stealth 6, SVS SB2000 sub, Emotiva DC-1 DAC.