I buy a lot of CD's of full-length studio albums, and there are a good number of bands from whom a new studio album is an almost guaranteed-buy for me. I rarely bother with EP's, I almost never get singles, and in the last few years have basically given up on live albums, compilations, cover albums, tribute albums, and various bullshit like that. I don't really buy DVD's anymore either, because the 4 - 5 that I have, I've watched once and never went back to. So it's not worth it for me. And I was never into owning multiple, slightly-different copies of the same album, picture discs, or anything like that. I want the one copy of the album that I'm going to listen to... I have no interest in extra copies for display purposes. I do on occassion get remastered discs, and that sort of thing, since that actually affects the listening experience. But I'm not going to spend time, money, or effort trying to get some rare, out-of-print, North Korean pressing just because it's rare.
As for shirts, I used to buy 1 or more shirt at every concert I went to... after a while though, I got to a point where I simply had far more shirts than I'd ever need to wear, and I also began to realize that blank t-shirts are more utilitarian. Also, as the average price rose from $20 to upwards of $35, my desire to spend double-digit amounts for a $3 Fruit Of The Loom shirt with screen-print, waned considerably. For old-times sake, I'll probably continue to get a shirt when I see an Iron Maiden show, but other than that, it has to be a really fantastic shirt for me to spend that kind of money on it.
As for downloaded digital music, I am not opposed to it in theory. As my collection grows, storage and organization becomes ever more challenging. However, while I'm not as tied as some people to the idea of having the physical packaging, right now I still can't bring myself to pay for a download, much less one that is lower quality than a CD. Also, I'm not presently able to use sound files in my car, or my home-stereo equipment, and I don't have nearly enough drive space to store the amount of music I have on CD. For me, the technology isn't quite there yet, but it very well might be in a few years.