Craigslist is great however, in some cases you can get an item new and sometimes not. If you want new unused supplies then try thatpetplace.com, or drsfosterandsmith.com, or aquatraders.com, or aquacon.com, or as someone else said bulkreefsupply.com. All of these are very fine retailers and I have ordered from all but aquacon and bulkreef. But yes, I do agree craigslist is you best bet for cheap used and unused equipment. For example: i bought a 210 gallon aquarium, reef ready, with a stand for $200. That is only one small example of many of the great offers on craigslist.
Hope you find what you are looking for!