“eclipse’s” ideas (above) are all excellent, depending, of course, on the person.
I’m not sure how you came up with the $5,000 amount for the seforim store though! Depending on one’s financial means, even 50 or 100 dollars would be nice.
Remember this: Men are basically just older boys. We like our toys. So, other than seforim, most (not all, but most) guys like our adult toys, which, as eclipse mentioned, include things like electronic gadgets, tools, etc.