Based on the price, I personally would be doing an exit stage left. Too much on the line for me to absorb for any problems.
Now, if you want to go ahead, I would highly recommend getting in touch with someone like Diane (Color Your World) to print vinyl transfers and press them on with a heat press. I imagine she would even produce a sample for you to try.
I did about 350 nylon bags a few months back using vinyl transfers and they worked out fine.
Oh, by the way, I tried printing one with athletic ink and nylabond. It was a complete disaster.