I guess if you stock sustainers, some people will buy them (really glad to hear you're stocking OFRs BTW...)
FWIW I wouldn't be interested:
a: I use my neck pickup too much to sacrifice it for the sustainer
b: Finding "the spot" to get natural feedback is half the fun :)
c: If you have a Holy Diver bridge, you hardly ever struggle with b :twisted:
d: In the 80s I had a device for inducing feedback attached to one of my Charvels. It wasn't a sustainer, but a rather cumbersome device with a little speaker that you glued/screwed to the back of the headstock. Anyway, I played with it for a few weeks, but just didn't find it particularly useful & it went the way of those gimmicky FX pedals that you buy, use once, then stick in the bottom of your gigbag & forget you have :)
JMO, YMMV etc...