Go to hot deals and there's a Iwill mobo with 1ghz 266 athlon for around $180 I think. Great deal for a great mobo and cpu.
If you want to save a little more, then I'd say go with a Duron right now. 750 Mhz for $30 shipped. You can't beat that price, and then pick up the mobo A7V133 or KK266 for around $100. If you don't mind refurbed mobos, then the A7V133 is going for around $90 i think.