We have a Walmart , IGA , and a sav a lot in Beardstown--the last two firmly state they don't get , have , or cut tri-tip. Walmart meat mngr. says if they get a tri-tip in , it's unusual. However , they have at this point some nice looking Sirloin Tip roasts. Are these similar? ( thus my ignorance). Is it worth getting ? How would you cook it?