print or vinyl

[Quinsfan]

I have a customer who as decided with 1 week to go that they would like 16 red drawstring gym bags as a birthday party gift bag. I can get the bags but I am wondering if just subing them would be fine or whether to vinyl them instead. They are only going to have the names of the children on them with a silhouette of a Geko on them in black.
If I go down the vinyl route what would be the best product to use on 100% polyester. I know 123 flex may be an option but was wondering if anyone else had any preferences.

Cheers