I'm pretty sure that if I found a book I'd just bought was an autographed first edition, I'd keep it unless I had cashflow problems: unless there's some sort of

I'm pretty sure that if I found a book I'd just bought was an autographed first edition, I'd keep it unless I had cashflow problems: unless there's some sort of temporary fad going on, its present value is a pretty good predictor of its future value, and if you've bought the thing expecting to enjoy reading it then it doesn't become a less enjoyable read just because it's also valuable. (I guess you might want to be more careful about how you read it.) But I don't know much about how prices of these things behave. Maybe you expect that by the time you might be wanting to sell, those authors will have been forgotten and the books won't have any special monetary value any more?