It should of came with one. Did you get the $200 one? Best bet would be Amazon 3 days.

(3 s)[https://www.amazon.com/gp/aw/d/B013I9RLVK/ref=mp_s_a_1_1?ie=UTF8&qid=1486858191&sr=8-1-spons&pi=AC_SX236_SY340_FMwebp_QL65&keywords=3s+lipo+battery&psc=1]

(4s)[https://www.amazon.com/gp/aw/d/B013I9RSEU/ref=mp_s_a_1_3?ie=UTF8&qid=1486858270&sr=8-3&pi=AC_SX236_SY340_QL65&keywords=4s+lipo+battery&dpPl=1&dpID=41BMq3RoUYL&ref=plSrch]

Amazon is great especially if you get fast shipping. Local hobby shops near you would also sell batteries, but they would be more expensive. However honestly, a local hobby shop most likely would sell batteries with banana plugs, and I don't think pre-made adapters that go from banana plug to XT30 exist premade, while you can easily find XT60-XT30 adapters. You will also need to buy a balance charger to charge your new batteries. These chargers make sure all the cells in your batteries are charged to equal voltages, which is important in terms of safety and increasing the longevity of your batteries. I ordered my own batteries and charger from Amazon and they arrived in a couple of days, so if you're comfortable with using Amazon there's nothing wrong with the batteries there. Heres an example of one https://www.amazon.com/Tattu-Battery-1300mAh-11-1V-Airplane/dp/B013I9RLVK/ref=sr_1_2?ie=UTF8&qid=1485569927&sr=8-2&keywords=3s+1300mah