Mostly by not spending all that much on Transformers. I've gone years between buys, and when I do splash out I'll often get a whole pile at a discount rather than paying full price at stores.

Of course, it helps that I got into real estate recently, partly so I could fund Transformer-related expenses like BotCon trips. A couple of hours' work a year and six-figure payoffs mean a lot more free time and cash than I had working 9-5.