I know what you meant - don't let the name of his site fool you. He has the microline tubing as well.
I don't know how long the pieces are that he sells through that link, but shoot him a message and you can probably get what you are looking for.
If you want to order a larger quantity, the larger hose is 4mm or 5/32" (effectively the same, and compatible with each other) OD, the smaller is 1/8" OD. Polyurethane is the easiest to work with (that can take the pressures) and can have working pressures in excess of 200psi. Polyethylene is cheaper (you can snag a hundred foot roll for around 15 bucks after shipping), but kinks more easily and is nearly impossible to remove from barbed fittings without destroying it.
Since the Ion uses a mix of push to connect and barbed fittings, the OD is the more important measurement to make the PTC fittings seal, but depending on the size and material of the tubing you get it can be difficult (but not impossible) to work over the barbs. Just be careful of that bastard plastic barb on the solenoid - that was not a smart place to try and save a buck on SP's part.