LOW COST circuitsboard for diy amp !!!

I find this circuit boards And I don't know If the quality of the circuit is good. Does any one have some coments on the 400w amp. or others

http://valveaodio.tripod.com/schematics.htm

Im going to use the amp for a PA Systems. The amp have to be
"low" cost to build because it's going to be used in Ghana.
and I think that the MJ15004 .. is I good transistor ?
and okay price.

If any one have some circuits for building subwofer amp.
for PA systems.using activ crosovers. somebody told me that it can be build up using very low cost power transistors (mosfet) and still sound very well because it's only handling low freq.

If there is a circuit out there somewhere let me know!!!