Wow... That's kind of a loaded request. What I mean is...leet's start with turnover. If you want fish you'll wanna turnover ratio of around 15X an hour, for a reef it's 25+X an hour, and there are about a million ways to accomplish this.
Multiple powerheads, protein skimmer, pump return from sump, etc...
The cheaper route would be powerheads, but if youy wanna get a sump then that's another way...
Test kits. You'll want at least a kit for nitrates, ammonia, and PH.
You will need calcium, and alkalinity tests after your established...
Refractometer to measure salinity
Oh a powerstrip...you'll definately need one of those, LOL
A protein skimmer. Aqua C Remora is my favorite if it's gonna be a hang on, but again, if your gonna get a sump then you'll have more options...
Salt...you'll definately need salt
Heater or two