I did all my own painting and assembly, besides the jetpack, and spent about $3600. That doesn't include supplies, which I probably spent another $300 between paint, sandpaper, etc. I would think having the jetpack, gaunts, armor, and helmet all painted will have you looking at close to $6000 total.
Also, if you are paying folks to paint, it is also going to take a significantly longer time. It took me 6 months to paint everything, and I was only working on my own stuff. With commissions, you have to factor in that these folks are probably doing multiple commissions, all on their own time (most have a day job). So there will be a wait list, plus the time it takes to actually do the painting, plus shipping. 12 months is pushing it. It took me 9 months from start to finish and I bought a lot of my stuff secondhand. If you are buying new casts or pieces, the wait could be even longer. Sidearm, holster, and rifle tend to be up there. It took me about 8 months to get my fully painted and assembled jetpack.
To keep your costs and "time to market" as low as possible, you don't need to know how to sew, but I would definitely look into doing your own painting. I had literally never picked up an airbrush or even a paint brush before I started. If you get a good airbrush and don't cheap out like I did, and you really dig into some paint-up threads and look at the stencils, it isn't too bad. ROTJ especially is a little easier than ESB, at least the helmet. The jetpack is a bear. There really isn't a lot of "artistic skill" required, just patience and attention to detail. I'm an engineer by trade and I tend to do things specifically because I know I don't know how to do them, so your mileage may vary
Either way, good luck on your build, and may the force be with you!!