Why can't I find CD vendors in anime cons?

[smartalex2014]

I've been to Pacific Media Expo, Anime Los Angeles, Comikaze and Anime Impulse in Pomona. I couldn't find any good selection of CD soundtracks for sale in the dealer halls there. Other than those, there are DVD's, manga, toys, collectible cards, etc. It's not like cons in the past. The last PMX I've been to last year finally had some CD's for sale, mostly Love Live Idol School Project. That I like, but more of some Arcade game music should be there as well. Has any of you been to anime cons in the past like in the 90's (and not from a few years back)where you actually find CD vendors?