@circlip
I made that one using Aminet instructions, when it was double sided. It should be much easier now, that its single sided PCB. But the author himself says its just a 'hack'. The main problem with it, in my opinion, is that it has no extra RAM and you need that badly on a500.. The other small problem is that its not autoconfig, at least version I used.
Most difficult part is obtaining side expansion slot connector (86pin IIRC)
There is another project on Aminet with IDE, RAM, ROM from Russia but its way more complicated.
forget e-matrix unless you're millionaire..
A1200 is still your best option (unless A500 is very important), it really shouldn't be so hard to find one for someone in Europe and connected in a way to EU.
Look for it in "Amiga countries" like England and Germany, they are probably full of them.