Just some talk about our Copyright system...
Registering your copyright with the US Copyright Office allows you to college statutory damages up to $30,000 for each work of yours that is infringed and also lets you collect money from the infringer to cover your attorney's costs. Basically if you're registered, and someone infringes on your work, it will cost you NOTHING to bring them to court since the infringer pays your attorney fees. And you can get a good deal of money out of it from the fines.
If you don't register your copyright, you'll likely only be able to collect the monetary loss from their use (ie, if you would have charged $200 to license it for their use, you get paid $200) BUT you must also pay your own attorney's fees. It could end up costing you money, and generally isn't worth it...which is why you're encouraged to register your copyright with the US Copyright Office.
So when you find out an infringement happens you register your work and THREATEN legal action and settle out of court for say 5x-8x how much you would have charged or however much you want...the infringers generally don't want to pay your attorney's costs (and their own attorney's costs) and risk fines of $30,000, so you generally have some leverage over the licensing terms/price...so register your works...
Whether or not you are awarded court and attorney costs depends upon whether or not you win ;)...the reason it was not viable in the past to seek compensation for minor infringements, as I said previously, was the risk and the time loss was usually not worth the effort.
Proving the value of an item is extremely difficult as well...eg. if you steal a design I drew that was worth $750 to me, it is not worth the effort to take legal action against you ( or artists would spend 96% of their time in court..and would effectively lose money )...but if I could prove that you took that piece that was worth $750 to me and made 1000 lithos of it and sold each litho for $300, then it might be worthwhile to pursue it.
At any rate...whoever ' wins ' will have his court costs, lawyer fees, usual expenses paid...but there is no guarantee that you will win...even a registered copyright is no guaranteed protection...there's been many cases of people trying to copyright work that was not their's and work that was thought original but in fact was created by someone else.
It only affords you the protection of a date of registration that you can use to prove that you created it before he did...unless he can prove you wrong...and it does happen.
The weirdest case I ever came across was the Donald Duck case vs the Navy I think ( or a scavenger outfit ) ...it's been a long time since then...apparently some outfit was trying to patent an idea to raise sunken vessels by funneling ping pong balls into the hull...assumingly, this would work and create more stability and less stuctural stress when raising the vessel...
unfortunately it was discovered that Donald Duck had done just that in a comic book and therefore was covered under copyright...go figure! :D