Relax man, we're not talking about signing him on a 5 year max deal. However, a 3 year extension for 3-4 mil/year would probably be a good idea as it looks now (I actually would go even a bit higher). And , yes, for me he is the perfect 6th man, but I don't have a problem with him starting. Not instead of Willie, but with Willie. I don't care too much about this starter/non-starter debate. If Ginobili can come from the bench, so can Casspi.
The funny thing about him, however, seem to be that he is so committed to SAC that you don't have to invest in him. His present contract covers the next season. After that it looks like he'll sign with SAC anyway, if given the chance. I'm not quite sure what his market value is right now, but if he continues to shoot the 3-pointer the way he has so far, PO-teams (other that SAC) might get interested. Who wouldn't with his price tag. My personal opinion about him is that he is definitively worth every penny of his present contract. To me, as an appropriate comparison, Casspi is to SAC what Danny Green is to SA. So far Casspi is way the more valuable of the two and for less than 1/3 of the cost.