No syn free shop bought jellies I'm afraid. The hartley's sugar free sachets are 1.5 syns. I think the WW ones are a bit lower but you can just use 1 syn/20 calories to work them out
Lowest syns are sugar free hartleys jelly crystals all are 0.5 if i remember right. You could make your own free jelly like i do though, use sugar free squash and add gelatine.