Webrehm:
I bought the SSK custom barrel (not re-chamber) for about $325. RCBS dies were $100. That was 5 years ago. I assume you'll also want to sell your brass, which is valuable because 6.5JDJ brass can be loaded many times and because having it already fireformed has value. It is unclear whether you will sell the scope, mount, and rings as part of the package. If you're selling brass, charge more than what a person would pay for new .225 Winchester brass.
Charge a premium price for it: $200 for the barrel and $50 for the dies. See Ed's Contenders web page to see what other barrels are going for. Don't price it consistent with 7-30 Waters, get better money than that.