Bit the bullet and followed TT's and Rog's trains of thought.
5 metres of Iwis ordered up, with a few split links, from the Chain Man. Pleasure to do biz with.
That'll do 3 machines with bits over.
Note to self - take them off and clean the darn things more often! No excuses, must have a dozen dead chains lying around to make it easy . . .
Edit: In fact, there are 20 rears in the used pile, Regina, Renold and Elite, some with a bit of life left, plus the ones on bikes which are getting to the end. That's 20 years' worth, so somewhere approaching 170,000 miles on oldies as a best guess. Which, averaged out per chain, isn't so bad (maybe), at about 7 - 7.5K miles (11-12K km) per item - wand made unfavourable by a couple of early breakages. What do other people get?
If I dared keep a note of running costs, the biggest items would have to be tyres and chains . . . and oil. Will have done 170-odd 1000-mile oil changes on in that time, and with some consumption between changes that's got to be 80 gallons or 350-400 litres. Which in today's money - for the semi-synthetic Repsol 20/50 I use - comes to a number not to be discussed in the earshot of 'Erself. Doesn't bear thinking about so I won't. It's gone beer o'clock.