Hello Acid Modders,
Recently i stumbled upon the PSP Tool Battery at DealExtreme.com
It costs $10.50 and works great. (Used it to install 3.90 M33)
Also if you want a cheap memory stick i suggest the DealExtreme.com 2gb Memory Stick + Tool Battery Combo ($19.74)
Both items work great and this is the best deals for new modders!
DealExtreme.co uses PayPal for payment and is secure. (Shipping takes awhile)