You're cheapest kerbal to orbit?

[cerberusti]

I have one with an ISRU which can make minmus (or laythe), so if I am willing to wait for it to fill on the runway (or launch with less than full fuel) I can turn a profit from the trip.

A more interesting cheapest to orbit is probably minimum vehicle cost to get a single kerbal up there, without deducting recovered funds.

[Profit-]

Using KSPI-Extended technically it is free, and it is fun to watch the nitrogen tanks of reaction mass fill as I climb through the atmosphere... but I have roughly 200,000,000 credits of infrastructure...

[Vim Razz]

Ignoring the recovery angle and looking purely at launchpad costs, I spent some time goofing around this evening and was able to get this into orbit and safely return for 2,678.

[Johno]

Okay, but what about the early game phase, when you can't build spaceplanes? What is the lowest-cost method of getting a Kerbal reliably into space (and safely down again!!!) when you only have, say, the first three or four tech levels?

[78stonewobble]

Well, I still have a simple early liquid rocket handling all my tourist suborbital and orbital and near kerbin orbit needs. It's basically 2 early cockpits, 2 parachutes, 2 decouplers, mechjeb pod and the tanks and engines. No RCS or heatshield. Comes at a price of 11-15.000 or there abouts.

[sardia]

Ditch the decoupler. Instead, use the ground to decoupler the track from the cockpit.