I am trying to build my first board and will be using gullwing sidewinders I wanted to use this motor mount Additionally I weigh 165 pounds and would be using the board on mostly level ground with occasional hills. I want the board to go about 25-30 MPH. I already have 3 lipo batteries all 3s 5000 mah 2 of them are 35c and one is 50c i was planning on running them in series if i could. I want advise on weather or not the mount and batteries will work and more importantly what motor and esc to use I would like to pay about $150 for both I was looking to get the VESC as I see most everyone says it is the best and wanted to know the best place to get it for cheap (hopefully under $100). I also was thinking to get this motor http://www.hobbypartz.com/96m607-bigfoot110-5325-295kv.html i want this thing to be relatively fast and get the best i could for a good price. Any advise on anyaspect of my build would be much appreciated however I am pretty set on using Sidewinder trucks which i understand that many people will disagree but i love them for use on my normal longboard and would like to use them for this too. I also planned on getting generic 90mm wheels from amazon. Thank you for the replies and any advise i really appreciate it.
Some key advise when building things like this is not to be cheap
He has a high quality vesc for $105 (almost meets your budget requirements). I would also recommend his hub motors which are 90kv 90mm wheels (60mm motor and 30mm of black urethane.)
15mm 
I agree with @willpark16 I would also advise you to save up some more money and buy some quality and well documented parts. I promise you that you will end up buying the good parts anyway because the cheaper parts did not fit, were poor quality or just did not work at all.
i bought a kit like this and am regretting it immensely, trust me when i say its not worth it
If your looking for a Vanguard A-Like deck which is cheap then hit me up 
Take a look at my build. My original plan was with a budget of $500.
My FIRST BOARD, is going to cost me well over $1000.
Mind you, I started with zero tools, zero parts, and zero experience. Find a good mentor (YOU DA’ MAN @Namasaki ) and pick their brain.
I’ve been fortunate to have my hand held through this process. Trust me, there’s more to it then a few parts and “throw it together”.
You can see my build here: “The Frankenstein”
Up, top-right, you can click on the pencil and see all the versions I went though. You can also just read through and see where the “little things” like electrical tape and wiring will start to eat away at your budget.
I agree. I bought one of these kits and it didn’t fit my Turnigy SK3 motor. I had to do a lot of grinding/modding in order to get it to fit. The gears aren’t the greatest ratio anyway (3:1). Buy this pinion gear, 3D print this spur gear (check any local libraries/colleges for a 3D printer), buy these Abec clones, and buy these belts (it’s smart to have spares). Sign up here to get @Shogu12 's $22 motor mounts. You’ll need some Caliber trucks for that particular motor mount. No need to shop online for misc mounting hardware. This should cover you for the motor related stuff.
Keep an eye out for my budget board I’ll be posting soon.
If you buy those hub motors they will fit right onto your truck, no messing around with gears and belts. 