Good catch, didn’t notice that the models repeated on the 10 bar units. However, I’d be willing to bet it’s the 7 bar unit, 10 bar would be pretty uncommon in industry.
I doubt you’d need a receiver at the laser cutter itself, that is only really necessary for things with short, high bursts or air consumption. That would be more suited to the metalworking area, with high uses of air tools. However the air lines in the building are of reasonable size so that’s still not real necessary with a large tank at the compressor.
I’d set a budget for it and still try with that auction. A new Chinesium air dryer for 600L/min is worth $1800. A new compressor is $2700. You score that listing for like $2k, and just cope with it being 7 bar is like half the price of getting it all new.
Do you know what the router needs air for? It doesn’t need to clear smoke and assist in the cutting process like a metal laser cutter so it seems a bit… excessive… to use 400L/min just to clear the dust (not to mention that’ll make a lot more mess).