Cheap? Don't know-probably none of them. But, if you want them to last 20-30-40 yrs, maybe you don't want the cheapest. I don't know their life expectancy...but should be 20-40 yrs. I understand tubes will wear at the elbows. Probably depends on a lot of things.

We have Brock system & I'm happy. No experience with others. Maybe they're better-don't know.

2 main differences determining size/capacity. We had choice between 4" or 5" system. Chose the 5"...it has more upgrade possibilities. I'm guessing the only downside is cost of pipe & fittings. Then, I believe the air pump is same for most all capacities within the 5". However, for more capacity, they use a larger motor & keep changing the drive pulley sizes to overdrive the pumps. At least that's the way it was 2 yrs ago. So-you could buy a 5" w/a 20 hp motor now & potentially upgrade down the road to a 50 hp motor.

I'd recommend 3ph or convertor. We're very glad we did that now & sorry that we didn't do that 30 yrs ago. We can't get 3ph power realistically. Co-op wanted about $120,000 (per engineering study/quote) to run the poles/wires 2.5 mis to our place. That only brought it up to our yard. Then more costs.

I think that if your dryer dumps that often with only a minute or 2 of downtime you'd let it run. I can't think of any downside to letting it run. It doesn't draw many amps while no-load. The blower mechanism itself incorporates a timer to make sure the system is completely empty before shutdown. Then of course, I think you'd want blower to start BEFORE you dump corn on top of it. We're dumping out of a Shivvers bin into our blower...so it runs a little longer per cycle depending on initial moisture. It's completely automatic on startup/shutdown....for us anyway.

Check w/your dealers & price a couple different scenarios. If you're wanting it for this fall....you might get started soon here....unless you're in Australia or something.

http://imageevent.com/lukowphotos/farmingmachinery/2004homebinprojects