In SoCal Ralphs occasionally puts untrimmed Tri-Tip on sale for $2.99, usually select grade, but last time it was choice. Secret trick: when Ralphs puts select grade TT on sale, look for a Ralphs "Fresh Fare", located in wealthier neighborhoods, Ralphs "FF" only sells choice grade(& above) and have the same sale prices. Tri-Tip is a good cut also because you can visually judge the marbling, not quite as easy as a Rib eye or strip, but you can tell how much fat is within the meat. Unfortunately, untrimmed Tri-Tips can have A LOT of fat hidden under the meat depending on how it was trimmed, but Ralphs will sell "Trimmed" TT for $1/lb more, and can be a better deal if you have to do too much trimming.
I usually cut a TT into 2 pieces along the grain, then into 2" steaks that get a gentle pounding before seasoning both sides for a hour or so rest before grilling.