The future is now. Or at least, it's soon, and over $1 million dollars away for those interested, as Japanese company Suidobashi has announced plans to build custom, actual, operational mechs.
Named the "KURATAS", the vehicles will come at a standard price of USD$1.3 million, with additional accessories like shields and weapons available for around $50-80,000 each. You even get to choose the paint scheme.
While there's the whiff of a scam to the whole thing - especially given the fact we never see one actually moving on a road (and no, some bad CG of one rolling through Shibuya doesn't count) - there's at least one operational model that you can see in a promotional video below (which also gives a fairly comprehensive breakdown of how it actually "works").
You can see some images of the prototype under construction, and learn a little about the mech's creator, here.