My setups vary over time, but I definitely troll the lower end, price-wise.
My most expensive buy was $120 for a Pioneer SX-950, into which I put another $80 in parts.
My least expensive working receiver cost me $15.
Looking around at speakers sitting around the place, cost per pair, I see $3 - $60, with sub-$20 ruling the day.
Add a few bucks each for surrounds on the ones that needed them.
CD players and cassette decks tend to be around $5 - $15.
My one turntable cost $10 w/ cartridge.
Not counting things sitting idle, active setups only (not necessarily best possible):
Living room: Pioneer SX-950, Grafyx SP-8, Nakamichi CD3, Sony TC540: $200+10+6+18 =
$234
Bedroom#1: Sansui 771, JBL J50, Memorex DVD player: $70+3+4 =
$77, with $50 being parts to refurbish the 771.
Bedroom #2: Realistic STA-90, B&W DM303, Pioneer PL-7: $45+12+10 =
$67, again with $40 being parts to refurbish the STA-90.
Bedroom #3: Pioneer SX-1000TW, Cerwin Vega D2, Pioneer cassette deck and CD: $75+ $20+$5+15 =
$115, once again $40 in parts for the SX-1000TW.
The best-value full system that I could assemble from a few fully functional pieces would be:
Sherwood S7100-A, Warfedale W60E, Nakamichi CD3: $15+$7+10 =
$32.