Buy a 2nd hand MacMini,PowerMac,eMac or PowerBook with G4-CPU and install MorphOS (http://www.morphos-team.net/). Will set you down just 100-300 Euro (depending on which HW you choose) and will give you as much modern PPC-Amiga as one can get.
Just read the FAQ to make sure you buy a supported model.
you forgot to count in the price of morphos itself (over 100eur!).
