For that kind of range and speed at anything remotely close to your goal price, you're looking at DIY. Take a look at the BBSHD (1000W nominal) and Cyclone (3000W nominal) mid-drives with a 52V, 20-plus Ah pack (with an emphasis on the "plus"). The BBSHD will be easier to install, the Cyclone will be cheaper and can run at a higher power. Lunacycle is a pretty good go-to for purchasing: Luna Cycle LLC

Be highly suspicious of battery packs sold directly from China on eBay, Alibaba, etc.

https://electricbike-blog.com/ and Electric Bike Reviews and Reports / ELECTRICBIKE.COM have a lot of good information.

Be aware of local and state laws regarding ebike power levels and speeds.