Lets see... We currently stock
IJ35, IJ40, 180,480, 3290, 680, 180-LSI, orajet 3268, 1050HT, 3 Different window perfs, 2 different clears, and a few specialty vinyls we use once in awhile. Then add a matching overlam for each..
on top of about 30 reflectives for traffic signs, and 30-40 colors of vinyl for cut signs.
Our shop gets enough work that we cycle through all/most of it and have a use for each.
My other shop uses 3 different vinyls. One reflective, one intermediate, and one high performance, and thats all it needs because it's not big enough, and doesnt have enough clients to regularly stock so may types.
Depending on what you do... I'd suggest stocking 1 of each. IJ 35, 180, and if you ant reflective... you might be stuck with 680 with a latex, or 7930... but 7930 sucks.
You might pay more per SQFT by only stocking 3 vinyls, but if you buy a 50 yard roll, and end up using 5 yards of it a year... its just wasted money.
We've had a few specialty rolls we purchased for some jobs. i have a corner in the shop of "Dead stock", some stuff is 140 FT of a material, because we only needed 10 ft of it... and it's been sitting there for literally 5 years. Vinyl has a shelf life of 2 years in most cases... So I'd consider it garbage. But it's a $1000 roll, so of course they don't want to throw it out....
It's now my "Scrap rolls" that I use whenever I need to do head tests, test prints, etc. It's a very expensive test roll. So while you may have 10,000 choices... Only buy what you need, as you need it. Keep the main vinyls in stock, and don't buy something because it's "Cool" and you can find a use for it later on. Odds are you won't, and you'll end up with a roll of wasted product!