I'd say go the Amazon/ebay route and get a refurb phone. There are a great number of refurbs going for cut rates. Don't be afraid of "low end" phones, did you really need a giant screen and super clarity for netflix anyway? I've got my eye on the Kyocera Rise right now, which can be had brand new for $163 at Ting or even less and used on ebay (with a bit of risk).
Word of caution though, if you're new to figuring out the system, really read the details. I bought a Virgin phone off of Amazon for the fact that I thought I'd be able to activate it with Ting. Virgin uses the same towers after all, and the model was specifically supported by Ting. Problem was that Ting can't use Boost or Virgin phones, and the workaround hack is a giant hassle. Returned the phone, Amazon makes it easy. Ebay and Amazon sellers sink or swim based on their reviews and customer service, I'd give em a shot.
And yes, Ting CAN port a number after you've tried them out for a bit. That's actually my plan. :)