Hey guys, I'm in the market for a very lightly used (or new) extra battery for my D300; the Nikon-proscribed type is the EN-EL3e. On KEH, I searched EN-EL3e, to find this: http://www.keh.com/OnLineStore/ProductList.aspx?Mode=searchproducts&item=0&ActivateTOC2=false&ID=&Size=&BC=&BCC=&CC=&CCC=&BCL=&GBC=&GCC=&KW=en-el3e Two apparently identical batteries sold at different prices. Please note the "(synergy)" notation in the second selection. What's the difference? Obviously cheaper is better, unless I'm making a sacrifice of some sort.