Replacing carpet in a rental

[Ben P.]

My tenant just vacated my property after 4 years. The carpet is showing its age and looks dirty and stained throughout. The previous tenant had it cleaned but it's still bad. 

I'm looking for advice on what kind of carpet to replace with (high traffic / stain guard etc) and also where to buy it from. I'll probably leave the current pad since I'm trying to do this on the cheap. I was considering a place like Home Depot, Empire or Next Day floors. I'm trying to get the unit turned over this week so I can get a new tenant in there. 

I'm looking for the quickest, cheapest option I can find. I'm in the Washington, DC area.