The Fat bike fork offered by Bolton Ebikes found here https://boltonebikes.com/collections/frames-and-parts/products/fat-bike-suspension-fork is one of the most affordable, yet lightweight performance options for fat bikes. It has a straight steerer tube and is designed for quick release wheels. It is available in 3 sizes, for 20", 24" and 26" bikes.
How does it compare to the more expensive forks such as the RST Renegade, Rockshox Bluto or others? We have never done a direct comparison as they're not intended for the same types of use or bikes, so it's hard to do a side-by-side test.
The Sondors, RadRover, and other popular electric fat bikes use a less expensive type of front fork. A straight steerer tube and either bolt on or quick release front wheel make them NOT compatible with the RST Renegade or Bluto without significant changes. The name brand forks are designed for a tapered head tube and through axles. That means to use either you would need a headset adapter, along with a new front wheel with compatible through axle hub. In addition to the extra up-front cost of the fork, you would also be spending a few hundred dollars on a new headset and front wheel.
Overall cost of the fork available from Bolton Ebikes: $199
Overall cost to install RST Renegade, Bluto, or similar bike on an entry level fat ebike: $500 - $750
For aggressive trail riding I do believe you get what you pay for - the more expensive setup is likely to perform better and handle better on the trails. But due to compatibility changes it will come at a significant increase in cost.