What is taking up most of their time? What can you do to help reduce that, if anything?
We have tried: letting them create copies of content, letting them create drafts, and also letting them appoint other users to create content on their behalf.
"Should I increase my prices?" is a "vanity question" ( just like "vanity metrics" (E Ries Lean startup philosophy) >> They do not help you build a better business, they take you away from what is REALLY important) Finding why your customer do not want to spend more time adding content and/or why they consider spending more time adding content is not worth it definitely help.
Good luck.
How about letting them schedule and set future publish times for the items? As a small biz owner, if I'm in the groove of adding products, I would love to just spend 4 hours straight on a Sunday night adding all the products for the week and have the system publish them on a schedule I set. It's much harder (and more annoying) to do this fresh every day for 15 minutes than doing so in a large block of time.
If freshness of the content is a real concern, I'd pay for something like that to make my site appear more fresh.