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.
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.
"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.