I just bought the DDR Radeon from Buy.com for $162 - $15 gift certificate from techbargains + $0 S&H = $147. The default clock is 166 MHz (mine reported 164MHz in Powerstrip). I was able to o/c it to 200 MHz before sleep overcame me and I went to bed last night.
Radeon SDR's on pricewatch go for $130 + $10 S&H = $140.
Radeon DDR's on pricewatch go for $150 + $10 S&H = $160.
Dual head MX's go for about $130 + $10 S&H = $140 on pricewatch. This is where the second head is for DVI (for flat panel). You can get a dongle to convert DVI into VGA output for a CRT monitor.
I do not know about MX dualhead, but I have a Matrox G400 at work running dual displays under Linux and it works almost perfectly. The few issues I have with it are probably user ignorance in not knowing how to set it up correctly.

I am sure I can solve them given the time.