The BMPCC is really a camera for professionals who have a specific use for it. People who buy it just for casual use will most likely be disappointed, as it is not as user-friendly as, say, a handycam. Also, footage that you get from a BMPCC requires additional steps in your workflow in order for it to be even remotely pleasing to the eye, as it comes out in a very flat, RAW format that requires additional color grading. But it does come with a copy of DaVinci Resolve for that.
That said, if you are an aspiring professional, and you want to play around with the BMPCC, then here's what you would need:
The body comes with a battery, but you will want more than 1, as a fully charged battery won't get you more than around 40 minutes of use. But batteries can be purchased for around $15 per.
You need storage for your video, and the video that this camera produces comes at a high bitrate. So you will need not only a lot of storage, but a lot of FAST storage. Recommended is the SanDisk 64 GB SDXC Memory Card Extreme Pro Class 10 UHS-1. Keep in mind, however, that this card will only hold around 20 minutes of video from this camera because of the high bitrate (the extrememly high bitrate is what gets you such high detail in your videos), so you will want multiple cards. If you want to try and save a little bit of money on storage, you can try the PNY Technologies 256 GB Elite Performance SDXC Class 10 UHS-I memory card. Based on the specs advertised by the manufacturer, it should work, but try it at your own risk.
You need a lens. The BMPCC has an active Micro 4/3 mount. If you want to keep it inexpensive, you can get the Panasonic Lumix G Vario 14-42mm lens for around $165. I use this lens with my GH2, and it is adequate for what I do. You'll also want to put an ND filter on that lens. ND filters vary in price, but most of them are pretty inexpensive between $10 and $50, depending on what you get. Just make sure for this lens, you get a 52mm filter.
All of this can be purchased right now for less than the body of the GH3, so if you want to get amazing resluts at the cost of learning a new workflow, then this camera would be fun to try. Just remember that it does have a learning curve, and it might be a little much to take in at first if you just want something to shoot with while you're on vacation.