|Look at the link below to see all the flavors of AGP and diagrams of the notch placements. That should help you to determine what version of AGP you have.|
Without taking into consideration the pro stuff there are basically 4 versions of AGP. They are classified by the suffix atached to them. That suffix indicates the speed capability of the slot.
AGP 1x, 2x, 4x, 8x.
You can pretty much discard the first two if your motherboard has on board video. That leaves you with AGP 4x or 8x. MOST AGP cards and slots are backward compatible one version. So an 8x card will usually work in a 4x slot and will run at 4x. There are exceptions. I suggest you try to get a list of the available cards and research.
What is the deal anyway? Are you currently using on board video and want to improve? You may be able to buy new for the money you mention.
Below is a link to all the AGP 4x/8x cards available on their site now.