At about 30, lol. We built the first one to run off tractor hydraulics. Here's my two cents for what it's worth, been selling firewood a long time. The amount your doing prolly doesn't justify one as far as getting a return on the investment in a years time. If you plan on going and selling a hundred for several hundred cord, there is prolly no better option than a super split, 2500-3000.00, but what I would recommend for someone in your position is to go out and buy a 22 ton Swisher, made in Missouri, 8hp I/C engine and 16 gpm pump, decent speed, you can buy them all day new for around 950.00, I've got one I use in our commercial operation, it has never failed to split what we put on it, has been a very reliable machine. If you decide it's not for you it will be easy for you to get the majority of your money back on the splitter. If you do well and like selling wood and create a customer base you can always upgrade to a super split. I've also got a troy-bilt 27 ton and the swisher has been twice the machine as the troy-bilt for 500.00 less.
The troy bilt has split in excess of 700 cord, but it has went thru the pos Honda GC china engines, covered under warranty, we just put a 11 hp on it with a 16 gpm pump to get it where it needs to be.
As you know splitting is the bottle neck of wood cutting, if you can swing it a splitter is never a bad investment if you buy one that fits your needs and performance needs. For the hydraulics I'm really impressed with the Swisher's, like the fact they use a belt vs a lovejoy set up, we'll wear out two sets of love hoy couplers a year. The belt has a tension release so you can start the engine in cold weather without the pump being engaged, at 950.00 they are a fantastic value imho, if they'll stand up to our kind of useage they have to be a pretty hardy machine.