Buying last gen cards

Is there a good way to go about getting last gen cards?

My recent build used an R9 290 4gb, mostly because the introduction of the current gen cards drove the price down, and it's a decent single card. I left room in the PSU and case for another card, but I didn't realize how quickly the cards would stop retailing.

So my question is, is there a good way outside of stalking eBay or r/hardwareswap to find old cards?