I have a 30V, 20A power supply for sale. It is an adjustable unit, 0-30V and 0-20A (600W total!), built by a Chinese manufacturer. The list price is £380 from Farnell, but I got it for far less than that. I got two, donated one to the local Hackspace and was planning on using this one for a motor controller project but found a smaller SMPS unit that fit well on my desk so this unit is surplus to requirements. It's been used maybe ten times in total.
Will do 20 amps for about 5 minutes before the heatsink gets a bit hot (force-air cooled), recommend a limit of around 15 amps for continuous duty. I have lifted a quadcopter on this power supply drawing about 18 amps without a hiccup, and it will easily drive short circuits, though has a simple protection circuit which limits current to 500mA if it detects that it is driving a short circuit from the start. (To get around this, just disconnect the load, adjust voltage, then connect.)
UK only, will consider shipping for extra cost but prefer collection (Leeds, UK). £100 £75 £65.
It comes with no leads, no box, just the unit itself.