Lookup your school here:http://grad-schools.usnews.rankingsandreviews.com/grad/law/search/page+5
Click on the name, the free information on there includes the CoL estimate of the school.
I highly doubt their estimate will be lower than yours, mine calculated an above average rent/above average food budget/health insurance/transportation/way above average books cost and even discretional spending.
I tend to use about 60% of what they budget.
The biggest things you can do to shave costs is put some serious research into where you rent, buy your books used for 60-90% less online and then resell them for as much as you bought them (though if the edition changes that term, you're screwed for reselling), get a cheap internet plan (no TV and use a cell phone with limited minutes), drive only if you have too (it is sometimes costs less paying a bit higher rent to be closer if you don't have to drive), buy most of your food on sale and finally, don't buy stupid crap and go out to eat often. Get a comfortable chair if you plan on studying at your place.
Oh yea, find a high interest savings account to place your cost of living expenses so that the accruing interest on the loans won't be any worse than than it has to be.