If you look hard enough you can sometimes find deals in odd places. Like a Japanese website that sells anime merch, action figures and model kits. 
I’ve ordered 3 sets of slot files, a fret end dressing file, and a set of crowning files from them and I’ve been very pleased with the service and the product.
[redacted] I can’t find a PayPal email to confirm what I actually paid so I’m clipping this part out. In Yen it was 13,850 and 8,400 between two separate orders, there was a third I can’t find anything for, but that was in 2021 and with out a conversion rate. . .
Right now this set is ~$74 USD.
EDIT: Lee Valley also stocks these but I’ve not checked their prices, they were considerably more expensive when I bought mine.