Newbie with filtration questions

Hi
I'm planning on starting a salt water tank. I want to get a 55 gallon
tank and am planning on starting with a fish only system or fish with
live rock system and possibly later on converting to a reef tank. I
have done a lot of research and was planning on using live rock for my
biological filtration and also using a protein skimmer. When I went to
the store the guy said that if I'm not starting with a reef tank I
don't need the skimmer or the live rock. He said that the problem with
using live rock for filtration is that when the fish get sick and you
add copper to cure the fish the copper kills the parasites in the live
rock. The man at the store said I should get a wet/dry filter and a UV
sterilizer. He also said that without cutting any corners the whole
thing would cost between 1200 and 1500.
If anyone is willing to give me some advice I'd really appreciate it.
Thanks a lot
- Mark