I haven't appraised in a while, but this is from my recent knowledge.
Instagram:
17k personal - avg 1k likes / 2k likes on selfies. - $ As it's a personal, you couldn't really sell it as you can't transfer yourself to someone else. It only holds value to you.
67k stat - avg 6k likes / 2k followers a day. - $250 - $300 depending on the niche.
Twitter:
D*finite - $200
Skype:
P*trol - $100
Co*nc*dent - $80
Soundcloud:
Jesus - $20 there isn't a Soundcloud market.