awap:
What kind of a battery is that? With $.25 worth of O-ring and grease that battery should last a lot longer than my $2 batteries in my Data Plus.
Assuming that wasn't a rhetorical question, the battery for the Veo 200 is a lithium CR-2450 (see page 85 of the owner's manual), which the same as for most other similar computers. Available for a few bucks from a bunch of manufacturers.
For that price, I replace all our computer batteries annually.
I'm pretty certain the neoprene o-ring size is 2-026; which is 1-1/4" inside diameter and 1-3/8" outside diameter. Available for pennies each, though through mail-order you have to order a bunch at a time. Of course, according to the owner's manual, "Use of any other [i.e., not bought from an authorized dealer] O-ring will void the warranty."
Use of any other grease will probably do likewise.
Interesting, though, that they apparently encourage you to use any brand of batteries.
But I think (hope) the battery compartment is sealed from the electronics, so all you'd be risking (warranty-wise) is the battery. Your biggest risk is not seating the o-ring properly, which you'd be risking no matter whose o-ring you use.
--Marek