It's worth it if you're smart with it. I've bought a twitter for 120$ and sold for 200$ within the span of a day. It's easily profitable with luck.
If you're someone who is impatient then it's not the right thing for you.
Know your prices and be patient with them. Don't start selling lower and lower (something I do) to the point where you lose money.
Pick things that you think could resell for higher instead of something that's cheap.
Learn how to secure your crap so you don't lose a load of money. Also, be prepared for chargebacks, anyone can become a dick out of nowhere.
I just wrote my thoughts, so pick what you want from it.