Any experience with Birmingham Broker used cars?

We are heading to Birmingham this weekend to pick up a new/used Audi Q7 for my wife to replace the one that was destroyed by a texting dumbass a few weeks ago. So naturally, I felt it proper to do a search and see what OTHER vehicles may happen to be for sale in said area, and came across a Porsche or two listed by Birmingham Broker. Sell My Car Birmingham, Atlanta, Nashville ~ Birmingham Broker

Anybody have experience with them? Are they legit? It appears to be a consignment type service. I'm just wondering how this works legally, assuming it turns out to be a reputable operation. Are the cars still titled to the respective owners? Legally, would I be buying from a dealer or the owner? All things equal I'd much prefer to buy from an owner, as the sales tax on private transactions on older cars is much less than buying from a dealer.

 

Also, who would folks recommend for a quality Porsche PPI in Birmingham? We are buying the Audi from Tom Williams Audi/Porsche...any idea if they do PPI's or is there a good, trusted independent in the area?