Referring to my spreadsheet (oh yes I have a spreadsheet), players that I have seen play only once are (with actual appearances in brackets);
Mitch Walker (1)
Ross Flitney (3)
Mikkel Anderson (5)
David Gonzalez (4)
Stuart Jones (3)
Alistair John (4)
Anton Rodgers (1)
Ben Sampayo (1)
Dan Beck (?)...