is it possible to change a Pearl Mag-Vest Tube
tenor Carrier into a snare carrier? if so how much would it cost and what would i have to do??

If it's a j-hook carrier, you just need to swap out the tenor hooks for the snare version. The carriers are otherwise identical. Any Pearl dealer can get you those hooks, probably in the $25 ballpark plus shipping. (For comparison's sake, the Dynasty equivalent are $10 per hook from Lone Star Percussion. And they'd work with a Randall May mag-vest.)

That's not counting the snare attachment. If you don't have one of those, Pearl's new version can be had for roughly $50.