Before you purchase V1
Nikon 1 V1 offers really brilliant ballance between cost and performance, especially in 2015. But does that mean using V1 as videocamera will be cheap?
Getting the V1 body or the default set with basic lenses is just the beginning. You need to keep in mind that in order to achieve eye-and-year pleasing results, you will need to purchase some additional gear.
In most cases, you should not try to shoot handheld. V1 does not have any form of in body stabilization and only few lenses do actually provide the stabilization, called VR. So, you will need to get at least...
+ Tripod, $90 - $150
Solid tripod is the base, it should be robust, with ability to adjust yaw, pitch and roll via head to make it easier to frame the shot.
Rigs, gimbal stabilizers and other cool tech is also recommended, but not always needed. But these are also something to think about - even if just for rental.
Nikon 1 lenses
You will probably want to get the following two lenses, as they are flexible friends. The first one does combine fast aperture with small dimensions, and it is ideal for street video or for example interviews. The second one is flexible zoom for summer shooting, but don't expect much help in interiors thanks to its relatively slow speed.
+ 18.5mm f/1.8, $249
+ 30-110mm f/5.6, $300
Reduction for lenses
While the mentioned lenses are good, the Nikon 1 lens range is very limited, with very few fast lenses. You will need to get reduction for 3rd party lenses, even if just for the ability to focus manually via dedicated ring.
+ mechanical reduction for your preferred mount, $80-$100
+ FT-1 Nikon electronic reduction, $300
You just bought camera with interchangeable lenses. You will not resist buy new glass. Depending on your level of GAS (gear acquisition syndrome), this can be again additional $125 - $1000 for each piece!
Neutral density filters
Neutral density filters reduce the amount of light coming to the chip. If you plan to shoot outside, you will need this to be able to maintain reasonable exposure time along with fast aperture for that "oh-so-beautiful" bokeh shots.
+ ND4 filter, $75-$150
+ ND8 filter, $75-$150
+ ND32 filter, $75-$150
Advice: Buy as big ND filter as you can, and compensate the difference to lens screw via reductions (+ $15-$30 each).
The in camera audio from V1 is surprisingly good, but certainly not enough for cases like interview outside, club concert and other use cases. You will probably need external recorder, such as Zoom H2 or Zoom H4.
+ external sound recorder, $200 - $300
You will not want to risk running out of batteries during your shoot, so getting one reserve is good idea.
+ EN-EL15 battery, $50
Video editing software
You did not invest so much money to edit your footage in Windows Movie Maker in the end, so you will need to purchase a video editing software. There are some affordable solutions, and then there are some "final solutions", such as Adobe Premiere Pro.
+ software, $125 - $600
You just got yourself an excellent video camera, you will shoot a lot of video to get better and better, right? But you will need to store that HD footage somewhere. You will need to get...
+ 2TB video storage cache, $125
You also need at least two decent SD cards to store the video for you. Spare no expense and get one which will not fail you. Sony and Samsung offer some serious Class 10 cards.
+ 2x SD card, 2x$50
Shooting video with V1 is very exciting, rewarding and entertaining experience! But please keep in mind once you go this route, it can cost you $3000 extra during a year after purchase easily, if you go from a scratch.
That, of course, presumes you get all that gear immediately. You will. It is inevitable, but you may delay the process to multiple years, to easen the impact on your wallet a bit :)
You can do a lot just with tripod, 18.5mm lens and Zoom recorder, presuming you have already the software for editing and you will shoot indoors, mostly static scenes. With this, we are getting to more reasonable price range.
Just... don't say I didn't warn you :)