Angle Finder for Canon - recommendations?

[Carl]

I've tried a little macro photography recently with a back-to-front pancolar. I noticed a couple of things I wasn't quite happy with, which I think could be fixed with an angle finder. Firstly, the angle was very uncomforatable - looking down would have been much better. The second thing was that focus would have been better with some magnification (I'm using a film EOS Canon body, with a better focusing screen than the DSLR screens, but not all that good). However, the Canon angle finders are around $AU300 (~EUR150) - rather more than I'm willing to pay. I've found various third-party alternatives on ebay - are these any good?

Alternatively, perhaps I could find an old one from another manufacturer (e.g. Pentax, Olympus...). Which other manufacturers had the same sized eyepiece? Or could I get an adapter?

[Farside]

The Pentax Spotmatic angle finder fits the later EOSs, but I don't know about the earlier ones - it probably does, if the eyepieces swap over from film to digi EOSs.
A Pentax L-finder can be had for ~10euros if you keep looking.