Billboards For Video Game

We are looking for an artist in designing realistic looking advertisements for fake products in a sci-fi fantasy setting. We will provide the base concepts/mockups, and any other needed information. The final images must be in PSD format, with the text layer fully separate from the image layer. Aspect Ratios of the images must be one or more (Preferred) of the following: 1:2 2:1 1:1 Preferrably we would be able to take any of the submitted images and use them in any of those ratios, thus requiring the seperate text layer. Minimum resolution of 1024x1024.