I have a trip coming up and I already bought a regulator and looking for a computer right now and I actually already purchased one on ebay and unfortunately it didn't work, got my refund and continuing my search. I've been looking at the oceanic pro plus 2.1 which i found for $430 brand new on ebay. I realize everyone says the shearwater petrel or predator but I really don't have that kind of money at the moment. The main thing is my parents making sure i'm getting good deals and not blowing all of my money. I know this topic can go anywhere but with the budget, hopefully it helps. I just want something that's really good and under 500 also would like user replaceable batteries. I don't have a preference on wrist or hose mount. So this brings me to you guys... What do you recommend?