Don't worry about a bike being "too old" to put a reasonable amount of money into. If the rest of the bike is in good condition, it is well worth replacing one or both wheels to keep it on the road for another 10+ years of service. Personally, my favorite people in the world are those who junk, give away, or sell for next to nothing at a yard sale, perfectly good high quality bikes just because they've sat in the garage for 15-20 years. I've obtained several good bikes this way. I keep the best and flip the rest.

If the wheels you have were good quality, how about rebuilding them with new hubs? Saves some $$$ if you can do it yourself.