There is no right or wrong in a situation like this - it's all up to the OP on what he does.
If I got mugged for $100, I wouldn't care about the dollar amount, I'd pursue legal (and possibly illegal) remedies til my dying breath, just so that the perp thought twice before trying it on anyone else.
That's just me - I'm like the Energizer Bunny when I get rooked. Others are more easy-going, but it really comes down to doing what you need to, to sleep soundly at night.
If having money stolen from you is going to bother you, then do something about it. If not, then move along.