I bought what I could afford, which wasn't very much. I also pirated like crazy when I couldn't. Thing is, without access to pirated games and programs, I probably wouldn't have bought my Amiga in the first place as it was too expensive for me to justify for just a rare game here and there.
I'm not so sure how much of an effect the piracy really had, in that respect. I'm sure some people who could've afforded more games took the cheap option out, but I also know first hand that a lot of kids that bought Amigas and bought the occasional game never would've bought anything at all if they couldn't pirate, as they wouldn't have had any reason to buy the machine.
I think it is/was more of a problem of the market at the time. Today the average gamer is old enough to have plenty of disposable income. Back then, the average gamer was a kid that had to scrounge up pocket money and/or save up from low paid after school jobs.