I currently have an FSA Tempo compact double. Anything nicer I could replace it with that doesn’t cost the earth?

I had a FSA tempo, replaced it w/ a FSA gossamer, a 2-peice 24mm for about £28, really like it. Just kept looking on eBay over and over. Anything shimano goes for a fair price on eBay, buy FSA it seems to go unnoticed sometimes and you could grab a bargain. This is a good way to go IMO unless you really want to stick w/ a square taper.

Have look at Spa cycles. They do some nice Stronglight etc

If you are intending to stay with square taper to keep the same bottom bracket be aware that not all chainsets use the same length, and if you find new old stock (NOS) campagnolo they use a different taper as well. If you are just staying with square taper because you prefer it, have a look on ebay and see if there are any NOS Campagnolo Chorus chain sets, I doubt it, but they are very nice.