For your first game (Most say I'm wrong, but) you will need only one development cart. 99% of my development is done with an emulator. With major builds only being put on carts. You don't need anything but an Emulator and a assembler. That's it. CopyNES to me is the most useless piece of equipment out there, I see no purpose for it myself. You should probably pick up a copy of Super Mario Bros. and a copy of Duck Hunt, make two development carts (NROM-128 and NROM-256), and that will hold you over for a LONG time.
But first of all, I wouldn't even worry about getting anything on a cart until you can program the NES. Don't get ahead of yourself. You need to learn how the NES works, 6502 assembly, make graphics, make an engine, then you test on a cart. You don't just click the screen and go "Hammer brother here!" Building a game will take months on end of work. It will be tedious. It will be long. But if you keep to it and learn how the NES works and 6502 (The easy part.), working on programming a game will become fun, despite making not so much progress, you will enjoy it.
And you should pick only the right EPROMS for the cart and wire it so the unused banks aren't used. And then double up the program just to make sure it will never happen if you use a EPROM of a different size.
If you are serious about programming a game, don't make carts just to prepare for it. That's the last thing you will do. The "Make engine" step may take up many months to complete by its self!