No StG44 is going for anywhere near $1,500 if it's original. I think $15,000 might even be on the low end of an estimate (I've seen $22,000 as a serious medium range).

I collect WWII militaria. I have a lot of medals, badges, photos, helmets, uniforms, and other assorted goodies. Cost me an arm and a leg though, but a good investment in something that will (or at least never has) never go down in value.