I used to belong to a stampers 10 and inevitably I'd spend more than the minimum. I now put my $25 a month in a separate account and then spend it as a lump sum during Sale-abration to get the most bang for my buck. I then keep a running wish list all year. Paper must be bought first since I keep only a limited number of colours and then any stamps come out of the remainder. It hurts to make that $325 order so sometimes I even spend less. It's worked for me since I really think and dream about what I want.
I also tend to enter a lot of blog challenges. Receiving a little bonus in the mail often goes a long way to slowing down the "need" to have something new in my stash.