Definitely DIY, a dealer trip is an inconvenience and they'll probably charge you at least $100 in labor to do it.
Are you sure its the purge solenoid that went bad? I had the vent solenoid go bad, that was also an easy one to do, though a bit harder than the purge solenoid on the engine. Had to lift the car and take it off of the canister beneath the rear seat. Still something I'd never pay a dealer to do.