Well, if you own matching bookshelves that changes the equation a bit. Obviously you like the sound of those speakers so that has to be taken into account. Eosone was a company founded by Arnie Nudell, wasn't it? They sold thru Best Buy and were pretty heavily discounted. I thought at the time that they were about the best sounding speakers BB carried, although I don't think they'd be competitive today. They aren't bad, it's just that I think a variety of factors have created the current situation where very high quality is far more affordable than it's ever been. Direct sales competitors have certainly had an effect on B&M pricing.
I'd be leery of the dent, given how large it is. But if you are able to listen to them and they sound fine...maybe. It's hard to suggest how much a pair would be worth; I'm not sure how common they are. Given their age and the amount that were probably sold, I'd say 20% to 40% of MSRP is probably reasonable. Depends on the situation. If you want 'em badly and the seller knows this, expect to pay more. If they're commonly found and the seller really needs to dump them, you'll get a better deal.
You can get a reasonable idea of their value for free by looking them up on Ebay. I'd normally suggest A-gon but you probably won't find that brand sold there.
EDIT/NOTE: No knock on the Eosones, but given their age I can't wholeheartedly recommend looking for a pair of used Eo towers. Uses speakers are a great deal, but if you're thinking of starting from scratch you might want to consider something newer. Speakers can be a very subjective thing- what I love you may hate. Still, using the opinions of others and the recommendations of this site as a starting point, you can probably find something that may satisfy you more in the long run by looking at Monitor Audio, Infinity, Axiom, Paradigm, etc. Just my $.02.