"Is the CRV3 a propietary battery for this Olympus? Can I get it cheaper elsewhere? Because 2 of those would cost an extra $20 plus tax."
you can get it at office depot, target, officemax, best buy, probably anywhere they sell oly cams. this cam uses alkalines as well... or lithium aa also. the crv3 is expensive anywhere afaik (if not, someone please post deal)
"Is it better to get rechargeable batteries, or use the CRV3 batteries?"
up to one's discretion. lithium last longer, but when kaput, kaput. rechargeables take time to charge (1 hour to 15, depending on charger used), and they are NOT charged when just taken out of the package, like alkalines and lithium. it's good to have at LEAST one set (two pairs) of alkalines or lithium on a trip though.
hope this helps.