Should I stay with a newbie board or more flexible board or see about something less flexible? I figure that my abilities will improve, should I count on that and plan for the future).
There are 1000's of boards out there. How does one really start to narrow down the board choices?
You want to look for a board that best matches your weight, riding style, and skill level. A lot of websites have search filters for different categories like that, so just start plugging things in and reading around. Do your research!
What are the best options for purchasing? I can get a new board, or a used board. I don't mind the idea of buying used rental equipment (if that is a good idea).
The best deals are typically package deals (i.e. board, bindings, and boots all in one), but what's put together in a package might not be the best for you. A lot of people purchase online, but look around at boardshops near you to see if you can find a good deal too. Living in Colorado, I doubt you'll have trouble finding a boardshop.
When are the best deals? I know that it is getting to the end of the season, but when do the sales really start? How about boards that are a few years old (new boards, old models)? There is something out here (SNIAGRAB) that is equipment sales, but what are the deals like?
The best deals are now and over the next month or so. A lot of sites have had some awesome deals. Sierrasnowboard.com had a 50% off sale the other day that may still be going on. New boards, old models are fine. They might not have the "must-have, s**t-your-pants" brand-new technology in them, but they'll get the job done. Good thing is, they're typically cheaper too. From the looks of it, SNIAGRAB is just something run through the Sports Authority franchise. What I'd recommend is that you do your research, find what works for you, then see if it's on sale there. The problem with a lot of physical stores (as opposed to online retailers) is that you might feel compulsed to buy a tangible item on the spot that you think you may need. Be calm, be patient, do your research.