That UMI package is a genuine UMI Performance product. The seller is Hawks Motorsports who is reputable outside of eBay and appears to be a reseller/distributor of UMI. The price is the same as everywhere else. UMI Performance, Summit Racing, Jegs, Tick Performance, and Speedway Motors all sell it at $3,179. If you have a preference with one of those other companies, use them. Shipping might save you money, you might want to shop around as one of those places might do free shipping.
Sorry, when you asked if anyone heard of "UMI products on eBay", I was thinking a shady store on eBay imitating UMI. People do that with their store name. You see "UMI Products", think you're getting "UMI Performance", buy, and get shipped a counterfeit unit for half the price because it's "UMI" and the prices is too good to pass up. Some people don't even get the counterfeit product. Often something like Sunglasses or Doll House Furniture arrives, or nothing at all. By the time you've figured out you've been scammed, the shop is gone, accounts closed. ...no recourse.
Fortunately not the case here.
You can probably find honest reviews on YouTube and maybe just straight Googling. Personally, I don't think you can go wrong with any of these UMI, QA1, RideTech, etc. packages. It's all about physics and math. They're all going to arrive at the same geometry if doing their due diligence, so it's going to be down to your setup on camber, caster, dampening, rebound, tires, etc. which is all a personal preference based on driving style.
What is important is the control you have over those settings.
These packages go on serious track cars, and six-figure resto-mod trailer queens.