You can also offer that they only have to take what they want and can leave whatever they don't want behind (that saves them on cleanup and moving costs).  

Mindy, I think you got a few good 3rd party ideas here;national insurance company discountBig Box store discountBuildium, Appfolio or other property management discountHow about a discount with a clean up co. like Serve Pro or Got Junk. you could even see about Legal advice. or national painting companies.

It's also unlikely that they have done any updating and kept up on all the maintenance so a lower offer is more reasonable and you have a renovation opportunity.Come up with a list of services you can offer to make it easy for them to sell (as-is) and to move (clean-up service).