I've checked the Best Buy and GameStop near me. Neither of them carry any PSP merchandise anymore. I've checked online and all I see are sketchy third party batteries.
Does anyone know where I can purchase an extended battery, preferably Sony brand, for a reasonable price? If not, does anyone have any experience with a third party brand?
Please do NOT link me batteries you have not used that are not made by Sony. I know there are a ton out there and none of the ones I have seen have good reviews.
Amazon maybe? I would only buy from a store on there if it was fulfilled and shipped by Amazon. I have had great luck with real HG-duo (HX-32GB) memory cards that were not counterfeit. Yeah you could do Ebay as well, but don't buy from Hong Kong try to stick to the States (I mean only if you live in the states), and make sure its a real photo not a stock one. Oh, and ask the seller if the item pictured is what you will be getting if you win the auction.
If you have a Slim, you could buy a battery for a Fat and have longer life - that's what I'm doing.
I have experience with ones through Ebay, both of them made in China (Hong Kong)...
First one lasted 50 hours, then stopped charging (died).
Second one is what I am on now, a PSP Fat battery for my Slim. Longer life because it's made for the FAT PSP, and it's been running good so far (at 24 hours).
Bottom line is that the Chinese ones don't last as long as the official Sony ones, but the Chinese ones are CHEAP AS HELL and puts the official Sony prices to shame - a 'reasonable price' for a Sony-branded battery doesn't exist. You'll just have to prepare to replace the Chinese ones more often, but for the price I say it's worth it.