Hi there dary!
Marine depot runs good sales on things. That's where we bought our skimmer. Dr.'s Foster and smith is a great online and catalog resource as well and liveaquaria is an online option for stock. For a refugium, craigslist is a great place to find used tanks. Ebay is also a huge resource for CHEAP prices, and a great place to find things like refractometers, thermometers, etc. Places like Petmountain.com have good prices on some things like testing kits and powerheads. Shop around and make good use of google cause you honestly don't ever know where you can find good deals on this stuff. Also make a conscience effort to find a good reputable LFS
(local fish store). If you find one that really knows there stuff... You've found gold. They are out there but sometimes hard to come by.
Sand is a hot button issue around here. Some folks use pool filter sand and you should research deep sand beds to see how you feel about those. They make a great natural filter if you plan on doing natural filtration with live rock and a refugium. If you are patient, sand can easily be seeded from a few pieces of live rock. Other folks buy live sand in bags and use that. Search some old threads and see what you think about other member's ideas on sand. You'll quickly form your own opinion. We all do. Lol