Here's a longish thread discussing this very same Drueke set.
http://www.chess.com/forum/view/chess-equipment/what-drueke-set-am-i-looking-for
These sets are considered pretty collectible. I've seen them sell for up to $100 on ebay. Really depends whether they're in good condition, come with original box, etc etc.
Arguably the best plastic set made, and very inexpensive in its day. Your photo shows some use (dirt on the base) but very nice original felt with little if any wear. If you like your existing set, you can probably sell this set for a decent price, but if the rest of the set is in similar condition, it might be worth holding on to it as the prices will no doubt continue to increase. It depends on how much you paid for it. I have this set (the #35) and prefer it to any other plastic set I've seen or used.
I picked up a nice-looking Drueke set (complete, but no box or anything) at Goodwill a while back. 3.5" king, and I was wondering whether I ought to keep it or sell it on eBay. I like chess, but I'm just as happy playing with my existing set. Thanks!