But there don't seem to be any AF analyzer waiting me around nor selective voltmeter in a 400Km circle (while I have yet to see an old rascal OM). I'm not yet an eBay buyer, past experiences were not very good.
I fear that obtaining something for cheap like the for audio indeed great HP 3581 is obtainable only at ebay. Although this is almost "vintage" gear, prices from second hand dealers for such professional instruments are still rather steep.
If You really want one, what You need mostly is patience (and of course some luck to get one in good condition). HP 3581`s pop up once in a while at ebay. Mainly in US, more rarely in Europe. As they often go dirt cheap in the US (~100US$) even the high shipping costs to Europe can be worth it (BTW: USPS surface mail is still bearable, assumed You`re not in hurry).