How much should I charge for an 8" cake like this? I'm thinking around $100 - $125.

Yes, you'd have to charge that for all the labor in the make-up pieces. I'd be willing to bet many people would charge even more then that.

AI'd charge more for the makeup than I would for the cake itself.

AI wouldn't make that cake, but if I did, I wouldn't make all those pieces AND the cake for a measly $125.

Those brushes look great! What size cake is that? I am guessing a 9", which is a base price of $120, plus $100 for the make-up. If she wants it cheaper, less make-up. I would say 1 brush, 1 compact, 1 lipstick and the pencil for $30.

I haven't done quilting on the side like that except in a class about 8 years ago, so I'd have to make sure I could do it nicely, but if I did it with your level of expertise, an 8 inch is 24 servings so it would be at least $288.00 and probably somewhat more.