Yeah, custom builds for ebikes tend to be expensive. Bolting stuff on to a mass produced frame is cheap and ugly. But its getting better. Integrated ebike builds used to be $7000. Now you can find some nice ones nearer $3000.
Here is a $3500 Yamaha Wabash that looks like a winner (although at this point it may be getting a little dated)
https://electrek.co/2019/03/18/yamah...c-gravel-bike/