Join Date: Jul 2015
Location: Pennsylvania, USA
I've trimmed out many windows. Even with custom fitting jambs, it shouldn't take 8 hours for 8 windows. I can pull an old window, install the new one, trim and prep to paint-ready in about 75-90 minutes. I'm just a DIY guy. Pros can probably do that in an hour or less.
I don't really understand what prep work needs to be done ahead of time. I've always just used off-the-shelf S4S for jambs - ripped, cut and rounded over right at the job site. I guess maybe if you're doing something fancy with the stool it would make sense to prep them at the shop. I don't think I'd show up with pre-ripped jambs since they often need a taper cut due to installation issues with the window.
That said, I agree $30/window is light for full dressing. I'd shoot for $50 each. If $400 is out of budget, maybe meet at $300-$350. Including loading up your tools, clean up, etc, you'll still probably have less than 8 hours into it.