Lost the spare key to my 2006. (somewhere in Ethiopia - its a long story). Looks to me from the forums that Gen I (pre 2004) prius keys are fairly easy to replace using the 'rain dance' method but that Gen II keys require the $250 dealer visit. Have I got this right?
In general, yes, but prices may vary. Replacement fobs can be bought from the dealer ($$$$) or online ($$) but must be paired with your car by the dealer. That charge is determined by the dealer and whether your long story of loss in Ethiopia get's a sympathetic ear.
call all local dealers, play them off each other for programming charges. you can get the part much cheaper by searching online.
