It's only £4, but it has to be part of an order of at least £10 or they won't deliver it. So I've gone for that plus The Long Mars which I was going to order anyway.
If that works I'll think about paying ebay / amazon prices for the SODIMM, e.g. about a tenner.
I'm very tempted to go all-out to restore this as it originally was, which means finding an early-ish Mac USB mouse and the weird clear plastic speakers. But these seem to be seriously expensive, so unless I get lucky on ebay etc. it probably isn't going to happen - any USB mouse works, and I think I can plug in ordinary speakers though I haven't tried it yet. Not as pretty, but possibly more practical...
later - also, does this seem to be the sort of bridging thing I need to give the computer fast Wifi - the engrish of the description isn't clear!