Aye you'll find a lot of the collectors on Twitter are willing to help price stuff if you can't find it online. One of the shirts I had was a match prepared shirt from 1986-88, eventually got put in touch with an official club Historian at Arsenal who was able to tell me that it was either worn in a specific game by Paul Merson, or most likely a recycled shirt that was used for training in the seasons after as the kitman back then was a bit tight with dishing out new gear.
I got the Holland Italia 90 home shirt and the Juventus 96/97 away shirt both in mint condition off a boy on twitter for around £80 a few months back.