Linus Sebastian previously suggested Valve sell the device for $500, but the company didn't show much enthusiasm for the idea.
Popular tech blogger Linus Sebastian (Linus Tech Tips) believes the Steam Machine will cost $699 at launch.
Without access to Valve's internal meetings, it's impossible to say for sure. All they've told us is that they want their hardware business to be sustainable. I think that means $699.99, unless the market changes drastically. That's a bit above their current cost, but over time (as initial investments pay off and memory and SSD prices normalize) the margin will increase.
According to Linus, at $699.99, the Steam Machine will still be a "very attractive" offer.
Valve itself is not in a hurry to name the price of its gaming device. Most likely, the company will announce the cost of the Steam Machine closer to the release, as Microsoft did with the ROG Ally X.