You cannot buy $100 of bitcoin the way you are describing, you have to buy the entire reward, 25 + fees bitcoins each time, that's around $11000 at todays price.
can you please explain what you mean more, what is entire reward and why can't i buy in small amounts?
Don't waste your time in conversation with pedrog. Like most people carrying advertisements in the signature space of their posts, he gets paid by an advertiser for creating posts. He therefore has an incentive to create as many posts as he can, and isn't motivated to be correct in the things that he says.
He is posting nonsense, don't let it confuse you. There is no need to "
buy the entire reward, 25 + fees bitcoins each time". Miners in a pool can receive fractions of the block reward directly to their address in the generation transaction. However, you'll want to be aware that bitcoins that are newly mined cannot be immediately spent. They require 100 confirmations before you can spend them.