Yup, it has CVS CAE - so Tetricus II Caesar as its model. Reverse seems to be Mars. Won't get too much further than that, I'm afraid.
Interesting coin. I agree with Finn235 on Tetricus II. The reverse looks to be an imitation of types with Tetricus II standing right holding a globe and transverse spear: http://www.wildwinds.com/coins/ric/tetricus_II/Steinberg_35-714.jpg
Not super rare, but a nice looking coin. I suspect you'd max out at about $5-10 I purchased a tiny Tetricus imitation in decent condition for just $1.75, as a point of reference.
In a short answer, non-official coins were produced in areas where there were a shortage of official coins. Since there were no imperial mints in some of these areas (usually regions or provinces at the boundaries of the empire), the locals would make their own versions or "imitations" of the official releases. These are ancient, and circulated either alongside or in replacement of the official coinage. There are modern imitations which are generally referred to as "replica" or simply "imitation." The ancient ones are referred to as "ancient imitation" or more commonly, "barbaric imitation" Hope this helps
Oh, yes, the one I posted is considered a barbaric imitation of either Tetricus I or II with a Pax reverse. With the Tetricuses, the barbaric imitations seem to be more common than official issues.
The funny thing about barbarous imitations is that they are all rare, so none of them are. You could buy thousands or even tens of thousands of barbarous radiates and end up with no die matches and very few that are alike in terms of emperor, subject, style, and fabric. Thus, even though any particular example may be "rare", it is seldom worth more than a few dollars, because I've never met anyone who thought they could make any sort of meaningful collection of them. The only exception are totally unique coins; e.g. coins that are not based on an imperial reverse prototype, or else represent an emperor seldom seen on barbarous coins.
*most* are relatively crude and easy to tell. A few are of much higher quality and are difficult to determine for sure. For example, this one I own. The face on Constans is quite crude, which might mean it's barbaric. However, compare to this example from Arles which also has a funny head. It's hard to definitely state that my example is barbaric, but due to the extremely odd portrait and abnormal reverse, we can probably conclude that the first coin is a very well-produced barbaric imitation, and not an official issue of Arles.
