I bought a post ban bushmaster carbine.The rifle had less than 100 rounds thru it.I am having the upper sent to bushmaster to get a new superlight barrel.How much can i sell the 16 inch heavy barrel for?

Used postban, $125-160

probably less than that.

There might be an easier and cheaper way to do this.  Send your "postban" barrel (or complete upper) to ADCO, and have them turn it down to a superlight profile.  That's what I did.  

This was a "postban" Bushmaster HBAR that I sent to ADCO.  They threaded the barrel, and turned it down.  IIRC, the total cost was something like $125.  Their turnaround time is usually about a week, and their workmanship is excellent.

Quoted: probably less than that.

I sold 3 of them right after the ban ex[ired for $110 each shipped.

Quoted: There might be an easier and cheaper way to do this.  Send your "postban" barrel (or complete upper) to ADCO, and have them turn it down to a superlight profile.  That's what I did.   This was a "postban" Bushmaster HBAR that I sent to ADCO.  They threaded the barrel, and turned it down.  IIRC, the total cost was something like $125.  Their turnaround time is usually about a week, and their workmanship is excellent.

Though I do agree that ADCO does great work, this is NOT one of those times I'd suggest profiling.  If you buy the barrel from Bushmaster ($205) they will install it FREE.  Even if he sells his post-ban barrel for $100, that's still only $105 invested, PLUS he'll have the true .625 FSB rather than a .750.

You're on the right track...