Costco in most areas of the country stopped selling try-tips a couple years ago. Cooked a 2.5 lb from TJs last evening. $6.99/lb, but I'm not a huge fan of the quality of meat from TJs. It was not as tender as I like. But much cheaper to buy and easy to find.
I've bought tri-tip at TJ's all over the country. They have always been the same. Look for whole tri-tips. They usually have plenty, marinated and plain (I prefer the plain as well). Some TJ's also sell tri-tip steaks, i.e., tri-tip that has been further cut into steaks. But I have never been to one that does not sell them whole.Your TJ's must get different TT's then ours.
The TT at my local TJ's were large chunks and did not resemble a tri tip at all.
I'll have to keep checking, maybe I'll get lucky.
Tri-tip is available at costco in duuth, ga but only marinated I have seen, rosemary and garlic, or steakhouse. Last weekend Kroger also had them, plain and several different flavors, but I didn't see them there tonight when I went to grab some coal.