Technic carnival is the perfect dupe for OPI Rainbow Connection from the Muppets collection, and is a heck of lot cheaper at only £1!
Technic is available at Bodycare however they don't always have this specific shade in stock. You can often find this on eBay however expect to pay a few quid (you know how these eBay sellers like to charge over the odds for hard to source items).
I've tried this polish over a few different colours but I find a layer over Nails Inc Saville Row to be my favourite combination so far; the contrast of the primary colours against the deep glossy plum is so striking!
Do you have this polish? Do you own OPI rainbow connection? What is your favourite combination?