Michael P. said:
I also thought the DPI was 70 for the pixel to 5ft ratio.
DPI is actually pretty meaningless for images which nobody intends to print. While some image formats store DPI information, it's only actually used (if at all) by the printer. The standard web image filetypes (PNG, GIF, JPG) don't even store DPI information as far as I'm aware.
For tokens, not likely. The dwarf picture Kristin used for her example is 148 kb before being reduced from the original 847x943. Resizing to 251x280 in Microsoft Paint makes it 25.2 kb; you could store nearly 4,000 images of that size on a Base account.
PNG images (which you'd need in order to get transparency) will be somewhat larger as they aren't compressed like a JPG is, and background images will by necessity be bigger than 280 square, but you can still fit a good number of images without even upgrading to Supporter.