Yesterday I received my preordered copy of a new NES Music Cartridge called "Teletime". The music is done by Joey Mariano and the NES code is by No-Carrier.

According to Joey Mariano no more than 50 of these carts would be made, and as it's still available from his webshop, so I believe it's still possible to buy a copy if you wish, the price is $30 + shipping ($5).