I've used ebay before many times, just be diligent. The problem with these bazaar style marketplaces is much less accountability and LOTS of fakes.
Not the best prices, but it seems like Best Buy, B&H Photo, Costco, stuff like that, might be the better "straight from the source" retailers.
I don't trust Newegg anymore. Used to like them but they've been chasing the wannabe-Amazon rabbit and have been caught doing shady crap to customers.
You could attach an external drive to a slim laptop or low-power PC like a Pi, only accessible by yourself, and technically you've got a media server!
You can host things from a virtual machine on your main computer, with a chunky external drive attached, if you wanted. :) That's the fun part, you can start from basically craigslist or hand-me-down hardware, and expand as your knowledge and space allow!
You could also run services from a paid hosting server, but I don't think the returns would be great for packing tons of data on there. :p