Careful - don't think about it too much or you'll get "the bug" at least as bad as G.A.S. And unlike cameras, there are a near-infinite selection of unique images out there to be collected. I have to budget myself or I'll easily overspend on these things. Best is to do some research into areas that interest you, then pick one or two genres to collect, so you don't get distracted by every bright and shiny object to pass your peripheral vision.