I'll repeat Gleam's note: There are some great bargains to be had at places such as Assi Plaza or H-Mart as well as the other local-chain places such as Caputo's or perhaps Garden Fresh.
I bought one at Assi for $5/lb and it was just fine for marinating and slicing into small bits. You're not going to get a tough tenderloin unless you overcook it. It'll be bland, but that's tenderloin in a nutshell.
I might not want to use this for a Chateaubriand presentation, but if it's crusted with herbs, wrapped in pastry, cut into bits for kabob, stroganoff, chinese food, etc. etc. they can't be beat.
What is patriotism, but the love of good things we ate in our childhood?
-- Lin Yutang