About the cheapest way to go w/ riprap is shot rock. It is just rock the quarries can't run through their crushers.Depending on how much shot rock they have determines the price.If they have alot piled around, alot of times you can have it for free.Just have to pay to haul it.It is odd sizes of rock, from several feet across to just the size of your fist. One more idea,if you live near a concrete plant you might be able let them clean their trucks around your pond. A buddy of mine has two lakes...2acre 3acre...both are concreted completly around now and it didn't cost him a thing, just a little time smoothing out the left over concrete
