As with quantum computing itself, storing quantum money would require low enough error rates that you could successfully apply quantum error-correction (if error rates are too high, you introduce more errors during error-correction than you can correct). Before you hit this point you can't do the computations anyway, and after this point it is only a tiny bit harder to keep qubits around indefinitely. (Modern QKD works because you don't have to do any computations on the qubits, in addition to not having to store them.)
Less Wrong used to like Bitcoin before it was cool. Monthly threads popped up around the same time a pricing bubble brought mainstream attention last year. When the bubble popped, and price continued to deflate, discussion on this site stopped entirely. Was there a change of sign in the social status of the topic, is the topic fully explored, or has there simply happened nothing of interest over the last year?
If you are not familiar with Bitcoin, here is one intro I happen to like.
Kaj Sotala lists a number of previous threads on the topic:
Less Wrong seems like a good place to discuss recent developments, if one does not want to suffer the inanity of the officially unofficial forum. If you are not longer interested in Bitcoin, perhaps send your remaining balance to the Singularity Institute?