Glenn,
As the owner of a service focused electrical contractor, I pretty much use some base figures and modify them.
I don't really use software unless it is much bigger (roughly $20k and up)
+1 on all of that.
if you can define the scope of work clearly, flat rate is the only way to go, imho.
if you can't define, there is T&M.
i've got a pretty good idea what most of the stuff i do often is worth.
it really comes down to what your actual cost of doing the work is,
and how much you want in your pocket, walking away afterwards.
around here....
service change is $1,800~$2,800 depending on where and what is needed.
can lights are usually $100 a hole if you are doing a bunch of them.
etcetera.
when i'm quoting, i'll just pull a number out of the air, and go with that.
it usually works ok for me, and the one time in 20 it doesn't, and i have to
eat a dry biscuit, has been made up in time savings by not driving out to
20 places to give a number.
driving out is the death of your workday in so calif. most anything under about
$5k, i'll wing it. let's say i do twenty $5k jobs...... and eat one....
my profit on $5k is about $3k usually, profit on material and labor.
so, i make $60k on those jobs. but one tanks, and i walk away with zero.
so, make $55k on those twenty jobs. and save 40-60 hours of my productive
time, driving to bid,for the profit on a $5k job, which would normally be $3k.
can i make more than $3k profit in those sixty hours? well, yeah.
sixty hours of my billable time right now comes out to fifteen half days.
in fifteen half days, i can net about $18k. work is really good right now.
if work sucked right now, i'd be driving out to jobs more.
YMMV.