Convert Picture to Vector for Background Image

Attached is the image. Objective: Create a background for a banner we will be putting a logo on top of. The banner will be printed off with the dimensions of 9x4 feet. [login to view URL] That is a link to what we will need to build on top of Look at <[login to view URL]> to know what I mean for as a vector. Doesn't have to have the shadow you see from the different level of bricks. Use your judgement to decide what looks the best. Dimensions: We will be using this as a background for a banner that will be 9x4 feet. So please keep that in mind when making the vector. The picture I have doesn't really show this well. You might need to create some stone yourself. Looking to get this done as cheap as possible. Need to be created in Illustrator.