Auction is the best way to find hard to find fish that are rarely or never sold in LFSs. Price wise, auctions can be better or worse than LFSs depending on the supply and demand, and the level of competiton. But it is only fair to compare LFS to LFS or auction to auction, not to each other. I have visited LFSs regularly from Jersey, Philly to Maryland, and still rate TFP the largest in term of selection and total gallons. The one store that used to beat TFP in gal was Aquarium Center in Randalsstown, MD but it was closed 6-7 years ago. The next big LFS is House of Tropical in Baltimore, which is one caliber smaller and couple calibers more expensive than TFP.
For the poster about T. Mac, they are not easy to keep and highly susceptible to bloat and bacterial infections. My previous experience with them had been failure, one died after the other raising from juvies to young adults. I have never had T. aureus before and won't be able to tell aureus from T. Mac unless I can see them side by side.