I hadn't thought of that. However, much like you can get IBM support for
used Power boxes I would suspect that you could get support for used HMCs.
And there's always that shop that says:
"well, I'm just upgrading to an old used Power 6 and a 7310-CR2 is no
longer upgradeable anyway so what do I care about support? Heck I'm
replacing a twinax terminal and I never put maintenance on that."
I don't recall the last time I called in IBM hardware support on an HMC.