Edge and Lo
Pro Edge trems are available directly from Ibanez or from guys like Universal Jems (link above). If its shot and you replace it, it won't diminish the value of the guitar, in fact it'll raise it, provided you use an Edge or Lo Pro. Do NOT get a TRS, for example

I've been converted even though I've never even tried a TRS, but the one I've got on the 90HAM has never done me wrong, so I'm not arguing
-Alex