We've been trying to dial in a what little bit of a surf wave we can get from an old direct drive and was finding that I needed to have more weight and be able to easily move it.
Found these sand bags on amazon for $20 for a set of 4. I like them because they have a nice carry handle and holding roughly 25#, so manageable even by the kids.
Then I bought six bags of sand from Menards.
And had the kids fill them. Bags ended up holding roughly 30# each.
Worked well to be able to list the boat slightly and I had two full 60# bags left that I put up in the bow in place of my two daughters.
Nylon bags will lay flat and fit under the front seats too or I can put them under the observer seat and/or helm.
So for about $60 I have 350# of additional ballast.