Hi Dan,
You expanding your list of services? I expanded mine to also include some handyman services (deck and fence const. tilework, painting, minor repairs, etc) . Be carefull though, it can quickly get out of hand. I'm still out trying to get PW work but in the past few months I have been doing more handyman work than PWing. Even thought about posting a message to see if any of the other DFW pressure washers need an extra crew for bigger jobs or if they are looking for someone they can sub-contract jobs to. Would rather be PWing than doing handy work, But hey, whatever pays the bills.
As for caulking window frames I generally charge $14.50 - $27 for a standard 6' X 3' window or $0.805 - $1.50 per liner ft. The price varies based on the average size of the gaps being caulked and accessibility to the window. If the window is 2nd story or hard to get to, charge a little more. If the gaps average 1/8th inch or less, use the low end, if it is 1/8th to 1/4 in use the higher end because you will use more caulk and labor, sometimes two pases will be required to fill the larger gap. If the gap around some of the windows are larger than 1/4 in, I would suggest they call a structural engineer because they are probablly having foundation problems. If the large gap is due to foundation problems that have been fixed, on larger gaps (1/4 or larger) you might want to use expanding foam to fill some of the void first. After it dries trim any excess that oozes out, then caulk it. Of course you will need to charge more for that, probablly double the price for that window. Set a minimum charge that makes it worth your time, other wise you will have people wanting you to come out to caulk one window.
Hope this helps.
P.S. If either side of the gap you are caulking is a surface that will be painted, don't use a 100% silicone caulk. Paint will not adhere well to silicone caulk and will start to peel very quickly.