> I would love a tiny computer. Like the Efika, or RaPi. [...]
> A single core 1.8 Ghz G4 with Altivec would do the trick (if available).

Fastest G4 is 1.7 GHz MPC7448 for 267 USD, which would need a northbridge chip and onboard controllers for everything. Fastest SoC G4 is 1.5 GHz MPC8641 for 379 USD, which would need onboard controllers for everything except Ethernet. Why not do as Jim suggested and settle with the 1.8 GHz quad-core T2080 for 140 USD instead, which has everything integrated except graphics and audio? It isn't a G4, but who cares as long as it has AltiVec?