PFD's !!! And wear them! Attach signalling whistles to them.
Where are you? What type of sailing are you doing? This will affect some items. On the ocean or larger bodies of water, a hand-held waterproof VHF is good. If you are sailing where no one else is likeley to be listening to a VHF, the a waterproof bag for your cell phone.
Don't know the Getaway well - but in general a Cat Shackle tool is a must, spare drain plugs, mast bearings, a paddle to maneuver in port can be helpful depecding on where you are sailing - or if the wind dies, beach wheels - if you have to move it around on a big beach, spare shackles, cotter pins, ring dings and pins
A Hobie catalog will help you come up with more, as should the dealer or person who is selling you the boat