Tecmo Cup Soccer for the NES: Why so pricey?

[treismac]

While I wouldn't claim to know too much about the retro video game market, it does see that one easily discernible pattern is that sport games are, generally speaking, not very valuable. Which brings me to Tecmo Cup Soccer for the NES- why is this particular sport game so pricey? Price Charting has it at $35 and ebay sellers, likewise, have it priced in that neighborhood. Is it the soccer sim/rpg play mechanics or is the game just super damn rare and/or super fun?

[bb_hood]

Its a rare. Its a rare alot of people dont know about.
Same with pro sport hockey.