I recently visited a garage sale and purchased an old clip art/stock image collection from "Hemera" called The Big Box of Art. While the (windows) software itself provides an index and a browser, I was only interested in using the images and none of the software. Unfortunately, the image files were in a passel of zip files and included two formats I was not sure how to handle; Windows Metafile (*.wmf) and "HPI" files.

If you want a road sign font, you can pay $800 (for the full set) or you can make your own. You also have several other options like Blue Highway or the roadgeek fonts, although the latter is often criticized for being poorly put together (badly authored.) The creator of that set simply traced the existing fonts. I have no idea why, because you can download the "Manual on Uniform Traffic Control Devices" which contains all the outlines.