My neighbors have a sand arena and they use a King Kutter pulverizer. Basically like the one in the pics, but with two spiked drum rollers. Seems to do a nice job on their surface - though it doesn't go very deep. I've seen a couple of team penning arenas that use similar (but bigger) pulverizers.
I've got a 100x200 dirt arena. We show foundation quarter horses - lots of event types (reining, cutting, pleasure, etc). I usually condition mine with a row cultivator with a section of spike drag harrow behind that. Does a nice job.
I borrow theirs once in a while - The pulverizer seems to do a stellar job of breaking up the clods (go figure) and leaves a VERY smooth surface. It also was handy removing the leftover sod clumps when I had the arena done - it would collect them and I could lift the pulverizer with the 3PH and they'd drop right off in a pile...
I've got about $150 in my setup. Would I spend another $500 or more for the pulverizer? Nope.
LAXPatrick