Simple Dish Soap
There are loads of dish soap options out there, some with terrible chemicals, some with great smells, some that clean great, and some that don't.
When we're spending a little more (eg. for our rental properties), we like to subscribe to 34 oz. bagged refills from Common Good which get an "A" rating on the EWG site (for about $.53/oz).
But for a project like this, when we just need something clean and simple and fast and less expensive, this Seventh Generation dish soap with no scent works just great. Price is for a 6-pack (about $.16/oz).