Where to buy cheap band shirts for DIY ebay store?

I'm about to open my modified clothing store on ebay that focuses on customized (DIY Punk, Biker, Skate & Psychobilly) band shirts/corsets/dresses. I have a lot of fantastic, original, professional-looking designs, but I currently have no steady supply of band shirts. Would ebay actually end up being my best bet to finding cheap band shirts or are there any other alternatives I can look for? Gently-used or new shirt ideas would be great! Thanks!