At Best

It's a trading term. Like "at best price" or "best terms" or "best value for my client to whom I owe a fiduciary obligation to treat them well in the fashion of the principal-agent rule". So "at best" might mean the best price. It might mean the best volume...i.e. the client wanted 14 million shares at $21 or better. You bought them 1 million at $20 but then the stock went to $25. That was not "at best".

The term has nothing to do with where you go to get giant flat screens.