New high quality tape
I too have had mixed luck with used tapes. I have had very good luck with new tape purchased from an ebay seller,
the_little_warehouse. They have 12 inch pancakes, 5000' each pancake and 10 to a carton for $79. The tape is Quantegy 632, 1.5 mil meaning a 7 inch reel will hold 1200' and a 10.5 inch reel will hold 2400'. I'm on my second carton. Admittedly, getting the stuff onto other reels can require creative thinking as nothing but a studio deck will hold a 12 inch pancake. I rigged a Rube Goldberg contraption with a Revox A77 that works quite well.
If you're in the market for a better quality tape, I also make purchases from Splicit dot com,
http://www.splicit.com/index.html where you can get 7 inch reels of RMG/EMTEC for ~$23 and 10 inch pancakes for ~$34. Both these are 1.0 mil; 1800 ft on 7" and 3600' on 10.5" reels. They also sell reels, both plastic & metal, boxes and all the accessories you need for tape.
The RMG/EMTEC tape is a very low noise tape, excellent for live recording. It also yields a 4 to 5 dB higher output than Maxell UD and TDK GX tapes, popular until the early nineties. It may even be as good as or better than TDK SA/EE although I have yet to make that comparison. I have but one reel of the TDK EE tape that, according to the seller, was recorded only once. However, it is still all of 15 to 20 years old so that comparison may be unfair.
Their prices are very competitive.