Does anyone know which other model/make motorcycle rear shock will fit the NX5 ?

All I can find is a company called Mupo(http://www.lemickracing.com/products/details/510/132/suspension/rear-shocks/mupo-ab1-evo/mupo-ab1-evo-rear-shock-honda-rs250-gp) who makes a shock for the RS250 but never heard of them. The shock looks the business but not sure I want to spend that type of money...I have heard of people using an Ohlins unit but can't find it on their site ? Unless it's maybe from another bike and then re sprung ?

Also are the later NX5 shocks better than the earlier ones ? 96 vs 00 ?

Thanks,
Mario