Sure, I see what you mean.
I suppose I ought to warn you, then, that if you buy a $125 engine, then you are going to need to be a bike mechanic in order to keep it going.
Once again, it's really not all that hard and it is satisfying as well.
But if you are not interested or uanble, then I'd urge you to get a set-up that's a bit more price-ie, but more dependable. I'm not competent to suggest a particular one since I'm a cheap engine, cheap electric and pedal type.
But if you read more and more of these threads, you'll find yourself attracted to a particular engine more and more.
Good luck