Okay, I don't play 4th, but I do still gather my friends and we play 3.5, which is still D&D. I'm going to assume this means the battle grid map included in the back of the book.
Thing is, all you REALLY need is a graph book (and pencils obviously). I get a lot of satisfaction drawing everything myself, and I save a fortune by not buying all the official miniatures and cards and things. As long as the most relevant details are written down somewhere easy - I'm trialling having the basic hp, defence, attack rolls, damage amounts and saves in a 'stat brief' section for DMs - then all the stuff Wizards sell is unnecessary. Back on the topic of maps, it's fine to draw it up on paper. It's cheap, it's not so restrictive, and it's basic. The game's supposed to be about imagination anyway. So use it. It's not like you're doing anything illegal anyway (though the sales division might be saddened that you're not forking out for their 'essential' merchandise).