It's an excellent price, but I doubt for that price it is actually OEM. I would double check their feedback and see if they have been selling batteries for a while. A few shady sellers will sell enough odds and ends to build good feedback before branching out into other things that they scam you on. Happened to me with a MP3 player. Seller had good feedback but not from selling MP3 players then next thing you know bad feedback starts pouring in about the memory being hacked. By then it's too late, I'd already bought it and then had to go through the whole Paypal Dispute hassle.
A good eBay feedback tool is
www.toolhaus.org im 100% sure their oem and it states their new . like 99% rating or something and they have sold 113 of theese exact batteries .!

i saw on the selling history of the behold battery and someone ordered 5 quantity . im guessin to sell them for more than $10 each later. man u know what almost every single person gots the behold in my school ..lol..im serious . u atleast see someone with my phone out of 10 people or something its scary . nd most of them do not even know teles proxy hack. i showed this one guy (freshman) fish , and he was like wtf , how u di that and he wanted to re thank me, nd he started bragin to ppl around him bout me that " this yaman got me free internet "....it was historical. i told him go to behold forum . but hes dum soo idont think hes coming to the forrm.. man but ul be amazed how many ppl in my school gots my phone. out of like the whole high school l. like 40% or around there who are tmobile users got my behold ..its crazy .jajajajaja..let me show u the link to the ebay thing. nd theres like 15 days left for the sale . "buy it now " sale for $3.95 ...man im thinking bout it ... oh and f.y.i its a store or something its called all4slaes or something and they got if im not mistaken like 200 more in stock !