Let me know if you find a supply of cheap ones! Dont know if Cowlings have 2nd hand ones, Im thinking of getting one of their 4 chain Harrows to tow behind a quad.
Stitch 3 metal hand rollers together and bind them with a frame, then attache A frame
other than that go to the woods and fashion some hard wood rollers out of some trees and make yourself a Flintstone type roller
Or dig out your wallet and bung the local farmer a few notes to pop in and roll your field, many people do this, keeps everything sweet for the locals, and local businesses