How about this'n? This is a Planet Jr. "push planter" I use to plant spinach, radish's, and lettuce. Thet are GREAT for planting SMALL seeds that happen to be fairly round. Forget anthing with bigger seed or out-of-round seed (ie corn) There is no seed spacing variation. You get what you get. They usually plant fairly thick, relying on thinning the crop once it germinates.
They were once the best you could get for large scale planting of certain small seeded crops. Modern "air planters" are more accurate, more adjustable, and more practical for larger operations.
A NEW Planet Jr. row unit is well over $500.