If the plan is to spend your money out on the Strip and just need a clean, cheap bed, these are the lowest-cost ways to stay right in the action. Set your expectations and they do the job.
Ranked by what I would actually book on a tight budget.
A budget stay inside the famous pyramid, better than its neighbor next door.
South Strip, near the Las Vegas sign
About the cheapest room on the Strip. Basic, but central-south and walkable.
South Strip, across from New York New York and MGM Grand