Did someone say excrutiating detail? Oh I have everything from 2012 thanks to credit card bill summaries.
In short, $650 on lodging (mostly hostels but two hotel rooms - Hiawassee & Gatlinburg), $1,010 on food resupply, $30 on laundry, $1,170 on restaurants (with limited cooking skills trail food sucks and I needed/wanted to calorie up in town - not much alcohol), $440 on gear (shoes, new socks etc, fuel, aquamira) $40 on shuttles and $240 on sidetrips to NYC and DC.
That totals $3,580 for a 4 1/2 month thru. I don't feel I skipped anything but I did plan resupplies every five days and not three to avoid the lure of towns. I still took 22 days to avoid rain and for sidetrips though.
I'd agree on the $800-$1000 monthly budget for most. And you'll have to find out if you feel like trying to shave $ off or add $ on without takign away from the enjoyment of your hike.