[nat]

A budget is necessary if you have cash-flow problems or poor self control. And, if the former, you probably shouldn't be spending money on baseball cards.

If neither of those is true, the way to keep spending down is to assign a very low number to each card that you want, and simply refuse to pay more than that number. The number has got to be low enough that it's hard to find the card at that price. It's what I do, and it means passing on lots of things that I could "afford". I like this strategy better than an actual budget because it means that if several things can be found at my very low number, I can get all of them. On the other hand, it also means that there will sometimes be a month in which I don't buy anything.

Caveat: due to being married, some elements of a budget are necessary. If I spend a lot of money, or if lots of packages show up in the mail all at once (regardless of what they cost), it might be necessary to lie low for a while. But that's a "staying married" strategy, not a "buying cards" strategy, and applies as much to anything else as it does to baseball cards.