Being qualified and prepared for jobs is of course important: I have the former and do my best for the latter.
It'd be hard for me to convince myself to pay for interview prep when there aren't jobs out there and I'm not getting interviews. As much as I don't like to be the one 'flopping like a fish' at the last minute before an interview, how feasible is it really these days for someone who wants a 121 job but isn't given the opportunity to compete for one to go around purchasing seminars and interview prep?
That's a bit like telling someone they need the most expensive rifle in the world when there are no deer left in the forest, because when the deer eventually come, you'd like to shoot it as accurately as possible. I understand the logic, and it's not flawed, but it's a bit unrealistic.
I've read a lot of good advice in this thread, keep it up and thank you.