I cant beleive there is so few exhaust listed anymore for the evo sportsters made up till 03. there has to millions of these bikes out there and exhaust manufactures have all but droped systems for these, and the few there still are avaiable cost more than an arm and a leg. slipons are still out there but what if you want something more?
Mrsnipy

 

The exhaust systems are still available for the 03 and older bikes the manufacterers just done advertise them, and a lot of the new fancy models are not made for the older bikes.
As far as cost that after market has always been high the first set of pipes I bought back in 01 cost me over $400.
If you want cheap, look at Cycle Shackthey are still reasonable and one of the best asfar as performance is concerned.