[nobelium106]

This is pretty late, but when it comes to Cu and HCl, copper is only very slightly soluble in HCl, not enough for anything of  major quantity, although you can precipitate copper from this with the addition of zinc (not 100% sure, could be Aluminum. It has been a while since i have done the experiment)

[C6H8O7]

Easy to find strong acids are

hcl also known as muriatic acid hardware store
citric acid also known as sour salt (the sour stuff in gummy candy) try bulk bins at a fred meyer or a store that carries a lot of jewish food