If you do some searches you'll see several "startups" with prices. Check out the 42g bowfront FOWLR from last week.
Standard maintenance costs would be difficult to estimate based upon several factors. Your choices for lighting and pumps will determine your wattage demands. For example some folks will cut corners on return pumps buying a cheap one to save a buck. Well a 900GPH submersible pump could easily run you as much as 200W per hour to run as opposed to an Ehiem 1262 running at about 65W per hour. That's up to 3 times as much cost each hour, 24 hours a day. For a FOWLR you may only want about 3 T-5 as opposed to high wattage metal halides. It becomes difficult to figure as energy costs vary wildly across the country. If you know the specs for all of your electrical needs you could visit http://reefcentral.com/calc/tank_elec_calc.php
to try and get an idea of what your monthly electrical cost would run.
Other factors such as brands of salt can make a difference.
My estimates for you would be:
Simple electrics totaling about 235KWh per month at $0.17 AKWH= $40 a month.
Food supplies based upon average fish sizes for 50g, about $10 a month.
$50 for a bucket of salt @ 200G, 20G water changes per month, $5 of salt.
I'd figure about $65-70 for an average 50-60G FOWLR, not including fish, rock, or anything else.