don't take this the wrong way, but why do you want to start with a 180 with no reef experience? this is an expensive hobby. OH SORRY, welcome to michigan reefers.
best place to buy? i would buy used from perhaps one of our members. or start smaller if you want new.
opinions vary, but i would say an overflow filter is necessary. it takes the surface water which is the nastiest, to the protein skimmer to remove the scum. mother nature uses a simple process to remove surface scum, protein, funk. it's called waves. that throw the nasties on to the sandy beach humans love to lay in.
ask questions here, what kind of setup are you interested in. read books, etc. before jumping into a 180. unless you got money overflowing in your pockets, in which case i'd like to talk to you, lol. good luck and again, welcome .