Hi Spicher,
We've all been in that position
I try and work it out an an hourly rate that I'm happy with. I know many design agencies don't lift a finger for under $100ph but that's a different market as these 360's are quite specialised and ideally you probably want to make a living out of it if possible so need the work? 360's are an 'added luxury' in the promotional side of businesses so price them too high and you never get the job. Price then too low and your wasting your own precious time and probably end up feeling annoyed with yourself. Also depends which part of the world you are as to whether there's a lot of competition for people making them.
For the base hourly rate I work out how how long it takes to take the photo's for a single 360 then how long it takes to create a completed 360 in PTGui / Photoshop. Newer versions of Photoshop make it easy to remove the tripod area with the Content Aware fill so less time messing around with the clone stamp tool

I also add an extra 10 mins for time spent correcting any stitching errors. Sometimes I don't get any but I still like to include it and it all evens out.
That's gives me a rough timeline for a single 360 from start to finish then multiply it for how ever many 360's you have.
This doesn't include any KRPano work though as you'll have to work that out separate. For me I'm not super clever with coding so spend a lot of time on here looking for previous examples. You'll get to know who the 'coding wizards' are here on the forum and if there's something you can't do yourself, don't waste endless hours trying and instead get a quote to get it done for you. You can always go through the code later and learn from it.
Don't let the client take over the photo shoot. You know what works well with your skills in PTGui/ Photoshop and the last thing you want to do is spend hours on a 360 because everything was too close to the lens or the lighting was crap. Rushing in a photo shoot always means more time in Photoshop.
Quote them for travel expenses to and from the photo shoot so that at least covers your petrol.
Hope that helps and good luck with the project
Andrew