I went out and bought a nice top sirloin roast.
You usually can find a nice 4 pound one like this for around $12.
What I like to do is cover it in olive oil, worcestershire sauce, (I use Lee and Perrins), Lawrys Seasoning Salt, galric powder, and some black pepper.
1 hr uncovered at 350 with a half cup of chicken stock, then bring her down to 275 covered for another hr.
Now it's just a matter of letting her cool and getting your thin slice on. They key guys is to use a nice oven poof glass pan, preferably 9x9 that just allows the roast to fit for maximum au jus.