"He who marches out of step hears another drum." ~ Ken Kesey
Is that a 6/8 you're getting? Haven't seen anything smaller than a 3/4" NPT in on M&R stuff, but I haven't seen any of their smaller stuff either.
If your just doing something to get set up get a 50' air hose (red type contractors use for jack hammers and such) with Chicago type ends and two Chicago x 1/2npt adapters, it should be less then $100 for everything you need. The 1/2" reducers should not affect the flow or delivery in your case. You should have some sort of flex line between the compressor and chiller. 1/2" air pipe (black iron or copper) will deliver 18 cfm up to 75' @ 100 psi. 3/4" will deliver 30 cfm up to 100' Each fitting in a system is equal to 5' of pipe.