I've been looking for some TA or Stronglight chainrings myself although in 110mm/74mm and although not everyones favorite eBay is always throwing up stuff especially vintage and retro.
Perhaps I can suggest that you also have a mooch around some of the European eBay sites especially France (www.ebay.fr
), however, you might have to be prepared to ask the seller if they would post to UK (some listing are French posting only) and pay via a bank transfer as not all sellers accept Paypal.
I've got a few bits from ebay.fr with no problems both bike and non bike - the last thing was a set of DT Swiss XMC100 airforks bagged at a bargain price compared to UK ebay and paid via bank transfer. They arrived safe and sound and I was really happy with them (brand new unmounted and uncut steerer).