For me, GAS may be part of a real illness (or my case, a syndrome). A few of my friends tell me I am the most obvious case of Aspergers ever, so I don't just GAS over things, I obsess over them and learn everything there is to know about said topic. It sure has helped me make the right purchase every time I have to buy something.
For me, GAS is very related to viewing very cool pictures of very cool basses. When I see/play them in person I find that they're not very different from what I have (which are very cool as well). And I realize I don't really need another bass.