Hate to tell you, but sealed tapes go for around $10.00 a piece. I buy used ones for around $2-3.00 when I need them now. I have a Nak and I completely erase them before I re-record over them and that works out fine, no bleed through that I can tell. And good brands like Maxell and TDK rarely have drop outs. So you can try what I do.
I say that because I remember selling boxes of 10 of either Maxell/TDK for $18-20.00 back in the 80's, so $2.00 today for sealed is not going to happen unless someone is very generous. Indeed, with inflation over the last 40 years, and no new production to speak of, $10 a tape sealed is actually a "fair" price in today's market. Best of luck regardless.