Another option is to buy a good pack of kiloware ( one kilo or pound wherever it originates from) and attempt to sort it.
Last time I got a kiloware was 4 years ago with 1000s of stamps. That was an exceptional batch. Sadly that seller is no longer in
ebay.
That pack kept me occupied for more than a month.
If stamps are on paper, you can soak them, and even be busy for 2 months !
I learnt a hell lot about the French Sage and Sower issues in that one batch!
For $50, it provided enough entertainment and I even had something to show out after I was done sorting!
Think of it as another option!