Specification of MagSafe power adapter coaxial cable?
Solution 1:
Apple's Magsafe technology is patent-protected, and there's a good chance they used a custom-manufactured cable to make it even more difficult for 3rd parties to sell cheap relacements.
Ifixit has a page describing How to Repair a MagSafe connector which may be of use to you. Excellent close-up photos & detailed instructions.