Recording on DVD takes quite a bit of time. With memory sticks being quite cheap in bulk maybe that's the new way?

https://www.amazon.com/KEXIN-10pcs-USB-Flash-Drive/dp/B012VT1QLO/ is 4GB and since a DVD is 4GB this drops the price a little. Remember I take it that you are paid for your time and this is faster than a DVD recorder.

Another thought is to put it on the CLOUD and let them get it themselves so there is no media to deal with.