A Hobie 16 spinnaker? I don't think he'll be able to find one of those used in the US - no?
For a budget, I don't think you'll be able to beat a used Taipan 4.9 or other F16 spinnaker. The hoist height will still be pretty high (as it is on an F16 or F18) so you'll have to be conscious about maintaining main sheet tension while the spinnaker is up.