Evaluating sellers of iPhone 7 Plus Logic Boards

I acquired an iPhone 7 Plus with a little note on the back that reads "Replace LB". It currently boot loops at the Apple logo. I am unsure about the battery's health. I know iFixit sells a replacement logic board part. I know Amazon sells the part. I am also aware of sellers on eBay and AliExpress. Price ranges vary wildly, even for the exact same thing. I seek a logic board with 32GB of RAM with a black Touch-ID ready home button.

What kind of a crapshoot will I be making if I went ultra-cheap? I'll be looking at each seller's ratings and reviews, and I wanted to know else should I be considering.