I have bought the plastic feeders mostly and paid not more than $20 for the very large ones holding about 15 lbs of food, which is all I would put out in a day anyhow in each coop, run or tractor.
I have one metal feeder in the main egg laying coop and I still only fill it with 15 lbs of food every other day and it will hold 30 lbs. I paid $26 for it several years ago but dislike it so much I went to plastic.
I have to tell at a glance from the outside of the pen or tractor how much they have left. I prefer not to let it get moldy in the summer and with afternoon showers and high humidity it does.