There are some official signed artwork lithographs out there in the 1,ooo to 3,000 range with no doubt authentic signature. I think one at a good price would be a good investment because he is one tough autograph. Some of his artwork isnt the greatest though.
I've seen the signed Tempest CDs that went out to the pop stores and they look different than this, but again wait for a more experienced Dylan expert to chime in.