There are a few things to consider when comparing the Predator to other amps and amp/dacs. If you don't like the sound, obviously it's not worth it. I haven't compared it directly to a desktop amp, but it definitely sounds better than the iMod>Hornet combo I used to have. And whereas I returned the 2007 Headroom Microstack because I found it fatiguing to my ears, the Predator is punchy and full bodied without ever sounding edgy. And while I haven't had a desktop amp to compare it to myself, other reviewers have said it sounds more like a desktop than any portable they've heard so far.
But assuming it doesn't sound that much better than the Move2 or something else that's less expensive, what else does it have to offer? For one thing, a built in rechargeable battery which holds a 50 hour charge (or something like that). I've never run out of battery yet, even though I've left it on over night a few times. It also has a lifetime warranty from Ray Samuels. That was a big deal for me.
Finally, there's the customer service. I ordered mine on a Wednesday, and had it in hand the following Monday, even though my Paypal e-check hadn't even cleared yet. So maybe you can get equal or almost equal sound for less, but you can't get the same level of convenience and service imho.