I know there has been a lot of talk about 99 capes and whether they should be able to cross over to other accounts...

My idea is this:

If you happen to obtain someone else's 99 cape you can take it back to the person who sold it to them and trade it in for gp (I think 100-250k would be fair) or for experience in that skill with a formula of something like lvl * 10 * 500. (Formula definitely up for adjustment just needs to be a good reward but not too much that it gets abused) also I wouldn't be against the xp being available in related skills just for less xp maybe?

People wouldn't abuse this because it is way too expensive for a 99 cape but others could still have a good reason to hunt them.