Bart beat me to it. If you were wanting to tinker - Bart's group build would be the ticket for an affordable, but capable machine.
If you are looking for a more bind n fly style - I would research the brands that are compatible with your Spektrum. I'm not sure that the DJI phantom work with spektrum. there are others on the market now that are competing with DJI like Blade that may work for you.
If you are looking to start cheap to learn, and it's probably smart to do so, try a small "toy" quad for well under $100 or a simulator, and then move to the camera craft later.
I asked about the quality of video you were looking to capture because many look to jump in feet first, buy their first quad with the intention of starting an aerial video business. While it's possible to get good video from a gopro on these MRs, it's not typically for broadcast (although of course there are exceptions). If you're looking to capture great memories, IMHO a gopro is hard to beat.