The Blockhead Stem from cw&t costs $89, which seems pretty reasonable considering it's machined from 7075 aluminum.
Of course, you may be saying why on Earth would you want to put something so un-aerodynamic — with sharp edges — on the front of your bike.
Designer Che-Wei Wang explained to BBG:
The sharp edges are for aesthetic reasons. All the bike parts our there seem to focus on aerodynamics and weight, so we wanted to make something different. We [Wang and partner Taylor Levy] wanted to reveal the purest function of the stem, which is essentially a chunk of metal that has two holes in it. It's minimal and its fabrication is also simple. Starting with a solid block of aluminum the machine time required to mill the stem is low, cutting only what is needed to make it functional.
OK, maybe you're still not sold on the look. But certainly you can get behind their IP philosophy:
Blockhead Stem is licensed under a Creative Commons license. Take our design, modify it, make one for yourself. But please don't sell them because we need money to buy and eat dumplings. Give credit where it's due. We actually want you to go find your machinist buddy and see if he or she can make it for super cheap. We spent about a month searching for a quality machinist that can produce them on demand. If you find a better machinist please share.
Of course, this isn't full-on open source hardware because of the restrictions on selling modified versions of their design, but it's still close enough to make me smile.