Version control for binary files?

You should take a look at Boar, it is a version control system made specifically for large binary files.

Maybe there were performance problems in older versions, but subversion is great when it comes to binary files. I believe it only stores deltas, so you should be fine with the size restriction. Keep in mind that it also depends on the formats used. If it is compressed, making a modification may have an effect on more of the file, creating a larger diff. Binary diffs aren't as optimal as text-based diffs however, but still very usable.

Subversion even claims that their diffing algorithm works equally well on text and binary files:

Note that whether or not a file is binary does not affect the amount of repository space used to store changes to that file, nor does it affect the amount of traffic between client and server. For storage and transmission purposes, Subversion uses a diffing method that works equally well on binary and text files

Not sure if it fits the price range, but there are specialized asset management systems for Graphics. I think Adobe has one (Version Cue), but there is also Alienbrain.