I actually used to buy a blend they sold at walmart and it worked great! It came in a big 50 lb bag and it was only like $18. Supposedly covered well over an acre but i just put a bag per plot, (most of my plots are 1/3 an acre or so)... Unfortunatly i havent seen this particular blend at any of my local wallyworlds lately, They do sell Evolved Harvest stuff there and it works pretty well too.. problem is you only get about 1/4 an acre per bag for around $20.
Most Co ops will have some type of Oats and i feel like they all prettty much work the same down here.