Four AA (2800mah) and charger w/EU plug for $10
If you are a boldly-going battery explorer, there is a 4pk of 2800mah AA rechargables together with a charger which includes an EU plug if you are going to be traveling. This is offered for $10 by a third-party seller, but the order is fulfilled by Amazon, which means you get free Prime shipping, or free Super Saver shipping for $25+ orders. It has 64 customer reviews with an average of 4.5 out of 5 (three 1-star, two 2-star). However, there are a lot of one sentence reviews, no one posted in-depth battery-geek tests for these... These if you like to test out different batteries. Otherwise, you can spare yourself potential frustrations and testing and stick with Eneloops and other well-known rechargeables.
Speaking of Eneloops, if you are a Costco member, some of their B&M stores have a $20 special on a 8 AA + 2 AAA + charger + extras bundle - according to the Fatwallet forums.