The minimum price should be the price you're comfortable/happy/need to sell at.
For Example, if you really want to sell your domain for at least $300 but you need $100 to pay your bills so that is the lowest you'll accept, then your minimum price might be $100 because you can at least pay your bills at that price even if the domain is worth $800. Sometimes you might risk a lower minimum price to get more activity/bidders interested (Which can result in a higher sale price than if you had a higher min price), but you have to be willing to accept that risk and understand that it might pay off or it might not pay off.
You can create package sales on the NamePros Marketplace easily.
One of the most effective ways to liquidate domains is to run a winner’s choice auction where you have a lot of options and allow the winner of the auction to choose one or more of the listed domains if they win the auction.
There are also members on NamePros requesting to buy domain portfolios that you can submit your portfolio to: