I'm not sure you'll find much of a market for 30 year old brand-less, bookshelf speakers. I suppose it could be helpful to find out who the manufacturer was to list on a Goodwill donation receipt. I think the tax deduction may be the best bet. Otherwise I'd gift them to a friend or relative which is good karma.
Need help identifying these speakers purchased in 1992
Photos are hosted here. Thank you mystery solvers!!
https://photos.google.com/album/AF1QipN-8umvKS-Eatl7nywKtCuhVVb91j_4BN6npPFo
https://photos.google.com/album/AF1QipN-8umvKS-Eatl7nywKtCuhVVb91j_4BN6npPFo