If you own a Playmate Volley, when it comes time to replace the battery (mine has lasted 3.5 years and I teach with it), I happened upon a very inexpensive option compared to spending $166 to purchase one from the manufacturer or some other online retail store. On top of the steep replacement price, one store wanted to charge me $28 to ship it.
I'll fill in the part number tomorrow when I get home (currently at work), but you'll want to call Digi Key
and order the replacement battery from them. Part of the exorbitant asking price from Metal Tek (the manufacturer) has to do with the casing that houses the battery that allows for the quick disconnect feature. Well you only need one case so there's really no need to purchase an additional one. You simply pop the case open (8 - 10 screws), undue the terminals on the existing battery and reverse the procedure to install the new one - takes all of 10 min at the most start to finish.
You could probably find one at a local electronic parts store or maybe even an automotive store. I didn't feel like doing a bunch of leg work, so I googled the name on the battery with its part number, which is how I found the Digi Key site.
The best part is the price - $69 shipped (From MN - I live in NE)! The price of the battery was $52 & change plus $3.67 tax. It was a little over $12 to ship UPS. I called last Friday, they shipped it Friday, and I received it today. Very nice people to deal with, very professional. I won't relay the story that led me to this incredible money-saving find; it's not a pretty one. Needless to say this particular company (retail competitor of this site...sort of) has lost my business forever given the manner in which they my order.
If you have any questions fire away. It's a fairly straightforward process, however...and what a money saver!
EDIT: The part number of the battery in mine was no longer available, so they crossed it to a suitable sub. Same specs, dimensions, manufacturer - works like a charm. Here's the info you'll need to purchase one.
Batt VRLA 12V 17AH