Pretty much of all the possible options have already been given, but here's something you can try:
Since you've cracked your SP3, that makes your SP3 unique (by cracked, I'm thinking it's not shattered). Hold on to it and capitalize by walking your way along the path of becoming famous... to the level when people start paying for your signature. Once that happens, the value of your SP3 would be worth more than your signature alone - appraisers would be able to authenticate it to belong to you since no other SP3 in the world has those crack patterns and autographs. Now depending on when that happens, your SP3 would either be considered an antique or obsolete.
But on a serious note, you've got my empathy, man. Just hold on to your SP3 and use it less - don't want to lose or wipe off* those signatures in the long run. Keep it together with the priceless story it brings. Then either buy a new SP3 (perhaps with lower specs budget-wise) or wait for the next release.
*- I got two Jansport key chains personally signed by Skip Yowell. He used a permanent marker. Unfortunately, someone tried to test if the marker really was permanent and wiped off Skip's signature off the key chain, defiling the memorabilia and turning Skip's autograph into a worthless smudge of ink on this person's thumb. Now, how about that? Certainly sounds like someone needs more IQ somewhere.:wink: