So I own $1000 in bitcoin but I want to invest the remaining amount to accumulate a whole bitcoin. The prices fluctuates every second so how can I do this on coinbase? I believe this is called a market buy order and I've looked at the steps on how to do this but I think they're outdated or wrong.
You can use other exchange that you can use a buy order, i think coinbase do not have that option move it to other exchange and trade it there with foat or other stable crypto currency.
The price of coinbase is on that spot you can only buy and sell the time you want it and no buy orders.