yeah, you'll struggle to find one of anything.

Haven't got any thermistors, but have got 3 spare heatlblocks - what size is the one you want ?

Had similiar issue with my delta at the weekend.
Ended up buying 4 heatblocks and throats, was cheapest option for A single heatblock (I snapped a nozzle inside my original one)
mind you compared to buying 0.5mm nozzles that was almost sensible.
individual nozzles on ebay around £2.50.
pack of 20 nozzles - assorted sizes, including 2x0.5mm - £4 from amazon prime.

It's a weird market alright. The technology outlet guys are good folks. drop them an email, they might do you a deal on just the bits you want.