Yes like cex.io i thought, a group buy where you can sell your shares too.
But with lower price and fees.
But with lower price and fees.
Then its not a group buy.
You are renting your hashes, so its called 'rent a hash' or 'contract mining'. There are lots of these 'contracts' on ebay.
If you use the words 'group buy' you will mislead people because they will think you bringing buyers together to make a bulk purchase, which you are not doing.
Good luck with your venture!
