Pricing all the parts for 2 bldc motors, two vesc controllers, charger, etc for what I wanted to build here put me at about $400.  That was a bit high...

I have revised the plan.  Do what I can using what I got on hand, and spend less than $100 total for the missing stuff.

I grabbed two dead razor scooters off craigslist for a total of $24, and bought a bms board, charger, and nickel strips off Amazon fo another $32.

Parts arrived today.  

I have settled on a 10 cell li-ion setup.  That gives me 42-36v for my motors.  I am trying to work 5 cells in parallel into the thickness of the board, mostly.  I plan on building up the sides and carving out the middle.  That capacity will allow me to move to bldc later.

The motors from the scooters are rated 100w@24v, but tolerated 36v just fine.  I will need to watch the temperature of them and I could always just limit my PWM to 75% anyway.

 Time to make some final design decisions and get to work.