I have a tumblr blog that is making me about $300 by dropshipping...I plan to sell it for $2100. Where should I sell it..i know it has value seeing as it is making me money!
It's not yours to sell. You have an account but you need to check the Tumblr TOS to see if accounts are transferrable.
You can't sell them officially. Nowadays many of them selling their blogspot's. By chance google comes to know this, they will delete immediately. I suggest you to continue your dropshipping method to earn or try some best affiliate systems. Goodluck
You can sell it on DigitalPoint. You'll find usefull information if you google "how to move a tumblr blog to a new owner".
But tumblr really owns the tumblr blog. If you want to invest in something and then sell it, buy your own site/domain.
Just thinking if you are earning $300 dollars from it why sell it? there are more things you can do with it and have a lot of returns.