woot.com, Duracell AA rechargeable batteries $14.99
Just a heads up, www.woot.com has 4AA/6AAA rechargeable Duracell batteries with charger for $14.99 today only. Not sure how these compare to eneloop but it might be a good replacement for play n charge and regular AA's.
ive had plug and play kits for the 360 controller. and it never really held a charge too well. but i will admit there was a several times where the regular aa battery cover would crack or break. but haven't had any recently. the cheapest I've found the eneloop
4pk with charge was from adorama.
The eneloops are supposed to be the best but I admit I have zero experience with rechargeable batteries. I've been reading looking out for some recently and here is the best deal on eneloop I can find. $18.50 for 4 batteries and charger.