First of all, I’m guilty of falling into G.A.S. myself. It’s fun! All the nice tools you could get. For some it may be even more fun to *collect* than the actual process of making music. I can relate! ; )
Just make sure you don’t get overwhelmed. This can happen many ways and literally in seconds.
Don’t demo everything you saw on sale just because it is on sale. If you never was interested in it or you never even heard of it, why demo it at all?
Substitute! Now, whenever I buy a new toy, something else has to go. This is one of the most important points for me. A nice collection is neat, but do you really need more or do you feel you found a better tool for a specific task?
Set yourself limits! This might be budget or count or like in my case, both.
Take a sleep before any purchase! If you demoed something for 5 minutes and go to buy it straight out of weird feelings like how good it is or the sale is over soon, this is worst. Trust me. ; )
Bjørn