Bowmore Legend is the worst Scotch I have ever tasted. It defines the word "green" in a Scotch. But I love the 17, and I've got a Darkest on tap. I'll report on that later.
Bowmore 25 at $280 is way overpriced. You can get it for $160 at The Wine Specialist in DC according to
wine-searcher.com. If your local store won't take it in trade, and they don't have a stock of it themselves, I'm sure they know who would be interested among their customers. Just tell them that you want someone to buy something else at the store to trade you for it and to contact you. If you're a good customer, I'm sure you'll get a call.
As for it being worth more in a few years, doubtful. It's not like they can't make more, and it doesn't get better in the bottle like wine. Unless it's out of production, and I doubt that, there's no reason for it to increase in value.