It's ok. Just fill your filter with floss and foam for awhile.
Look for tanks which have no dead or diseased fish. As there won't be any fish for awhile, the chances of the parasites surviving is quite low although better to be safe by choosing a disease-free media than not to.
You may try to bring the sponge(new and unused one) if you want. Your lfs will usually have a plastic bag anyway. Then tell them to put it with water and oxygen to allow the bacteria to survive.