As others have stated, it is very hard to sell a car that has been customizied to the degree you are contemplating. If you are ok with that, feel free to proceed.
A few of things to keep in mind also is that when conceptualizing your two tone:
1) It is easier (and less expensive) to paint the top half of the vehicle, rather than the bottom half. If you do a bottom half, you will need to paint into the jambs, which adds cost.
2) Typically, darker colors on the top are more visually appealing, and are complimented by window tint.
3) Specify whether you want the paint line "buried" under clear, or if you are doing some sort of separater, ie: pinstripe.
4) If you want to do multiple panels and accent a body line, to bury the paint line you will need to re-clear that whole panel, adding additional cost.
5) DO NOT "cheap out" on the price!! This is something that you are going to have to live with every single day, and a cheap price does not outweigh a poor or average quality job. By the same token, make sure you and your shop are both very explicit on what is expected.
On the vehicle posted above, the front bumper cover, hood, roof and decklid were painted. A very cost effective way to go; as it is only four panels that needed to be painted, and to bury the line, only the bumper cover, hood and trunklid needed to be re-cleared. If they carried that color down onto the vehicle's body line, that would necessitate essentially a complete re-paint, as every panel on the vehicle would need to be re-cleared; excluding the rear bumper cover.
My last paint project here; just to give you an idea of what is involved:
