In message , dated Fri, 11 Aug
2006, Mark Fortune writes
Yes, you'll spend quite a bit.
Everybody and his dog makes power amplifiers. Try something else (which is small-signal and thus less likely to emit flames and smoke). For example, low-level active crossovers; 2-way, 3-way, 4-way, Butterworth, Linkwitz-Riley, Bessel, transitional Gaussian, Thiele....
Enough to keep you busy for 50 years. And there isn't a great deal of competition, at sensible prices, so you could sell a few on Ebay. There is other low-level stuff which, compared with power amps, is a doddle to get working if you master the design mathematics.
And you only need a +/- 12 V power supply at 10 mA. (;-)