[puddleglum]

My son got suckered into buying a 1000w ebike with an undersized battery pack. He thought it had a wiring problem cause it shuts down every time you hit the throttle hard. Turned out the BMS shuts down the pack from over current. He never got it running. Get a 500 watt kit or a bigger battery. How much do you want to pedal or do you want to pedal at all? Those direct drive motors don't coast well so you need to be under power all the time. Not a big deal as long as you know. 500 watts is plenty if you don't mind pedaling a little.
If you still want to go cheap and stick with 24 volts, look for a used Schwinn IZip or Currie EZip. It's low tech and not as good as BLDC in many ways but sometimes you can find a really good deal. You can move the parts to another bike if you want. I re-geared mine and I'm quite happy with it. It doesn't have much torque off the line but it will cruise at 20-22 mph. I like to pedal all the time anyway and it is great for a pedal assist. I get some assistance up to 25 mph on 24 volts and there is no motor drag when the power is off. Something to think about.