Lower priced Power lok, sure grip units on Ebay.

Has anyone seen or tried these lower prices sure grip units on ebay?

For Chrysler Mopar 8-3/4" Sure-Grip / Power-Lock Posi Unit - 30 Spline 8.75"

Wondering if they are any good, or not worth the money? I'm considering taking a chance at that price.

For Chrysler Mopar 8-3/4" Sure-Grip / Power-Lock Posi Unit - 30 Spline 8.75" | eBay