Create a Bulk Pricing fieldtype, add your column headers (e.g. 25+, 50+ 100+) and set the required quantity a customer must purchase to receive that price.
There are additional options to restrict the prices to certain user groups and to specify if the prices set include tax.
Price includes 1 year of updates.
$19/year per site for updates after that.
To install this plugin, search for its package name on the Plugin Store and click “Install”.