Depending on the price, I'm sure someone would buy it.
Why did you wire a collapsible stock gun to the back? Crane stocks I get... collapsible stocks with battery bags are just asking for trouble imo.
It's pretty beat up and sounds like you picked completely random, bottom of the barrel 'upgrades' for a lot of it.
I have no idea why you're calling it a custom MGS4 M4... it's just like any other M4 with a huge silencer (yours actually looks too wide and short), and your RIS isn't long enough to match the MGS4 one to begin with.
FPS?
Battery included?
How does the battery fit into/onto the gun?
Wireset? Motor? Other gears? Piston head and Cylinder head? Bushings/bearings? Spring guide? What kind of hopup unit? It sounds like a bunch of random parts thrown together, but you didn't tell us about the other parts in it.
If you decide to sell it, good luck... I wouldn't expect much from what so far looks to be a very run of the mill gun.