I was in my local ASDA store this evening, and noticed a promotional display of Duck brand "DuckTape" in assorted colours, and assorted patterns, like leopard-skin. The ones that caught my attention were bright pink "Piggy Bank" and lime green "Twist of Lime". It occured to me that the pink especially would be a good choice for partly wrapping a pinpoint probe, to help find it when lost. I sometimes use markers to mark findspots and aid pinpointing, they are just 6cm diameter card circles cut from packaging (eg. cereal boxes), and I found bright pink to generally be the most un-natural stand-out colour.
They were all priced at £3 per reel, 9.1 metre reels (not the 15 yards mentioned on Ducks' website):
Here's the Duck website link:
http://www.duckbrand.com/products/duck-tape
Note they also make glow-in-the-dark tape - may also have its uses...
A quick search showed that some sellers on eBay stock these tapes, so they are not exclusive to ASDA.