The USB+ Dialogue II runs about 250$-300$ new. For a slight additional cost, you can often find the Constantine or USB+ Constantine for 280-330$ new. Their constantine is a soild budget NOS DAC for the price, and a nice first dac. I had mine for quite a while, and I was really impressed by it (though I eventually upgraded to their Paradisea+). I have not heard the Dialogue II. Since they are so close in cost, you may want to contact them and see if they can share more information between the sonic differences between them.
Aside from the sound, you can rest assured that his work is very impressive, both the circuitry and case, as well as the engineering aspects of it.
It's a shame that these DAC's don't get more notice here on Head-Fi.
Good luck, and keep us posted!