I'd buy them separate if I could even find any. I'm like you, I can find them online no problem but it's a bit risky buying one online as the quality of the motor/boat can't be seen with your own two eyes, and the shipping is so freaking expensive, I'd pay half the price of the boat to just get it to me.
You should check out Bass Pro or Gander Mountain. I really don't know what other dealers are around you. Are you wanting it for a lake,pond or river use?