Yeap - It would be really nice to be this way but developing such a feature like "auto-quoting" would really increase the costs. It might be a little bit counter-intuitive at the moment, but hopefully we'll be developing this soon.
Either way, clearly you're already calculating this value for billing, no? Or are you just using laser run-time for the bill, and estimating that based on the user's guesstimated path length?