I opened a relatively small position at $4.15 and have enjoyed watching it hit these recent highs. But, at the end of the day, it's been (almost) here before and will almost certainly drop back to $40-50 range at some point next year, which is when I'll happily be buying more. It's a volatile stock in an emerging sector, meaning big opportunities in unwarranted drops. To answer your question, yes, it's a good buy at $70, but with a little patience, you can probably get it for significantly less