OMG, I can't even go into the fabric store anymore. I tell myself I will "just look" - yeah, right, like that ever happens. So I don't go until there is a member's sale where I can get 50% off (almost) everything in the store. It happens several times a year. Fortunately, the fabric stores are not in my neighbourhood so I have to make a specific trip to get to one - no drive bys.
Now the internet - that's another story. I have to try and do the same thing: don't even go on fabric.com or quiltfabriccloseouts.com, because there is always something on sale that cries out to be in my stash. I do keep track of what I spend monthy (for everything, not just hobbies - utilities, food, dog, etc.) and over the past couple of months it's been, ahem, a lot. I keep telling myself that once my sewing room is finished, I will be able to see all my fabric and won't be so tempted to buy more. The theory being that since it is all packed up in bins I can't see what I have and therefore it's OK to buy more...out of sight, out of mind.
There was one month last summer when I was working on vacation scrapbooks that I spent $1,000 on scrapbooking supplies. Yikes! So now I can't even go to Michaels' to "just look". It's like chocolate and potato chips: if I don't have it in the house, I won't be tempted.
It's an addiction, that's for sure. :-)