You've Been Framed

I went to a store once about custom picture framing, and boy was it expensive. I had no idea that building a frame could cost so much. I also can't truly understand the need for it, as there are plenty of nice looking pre-fabricated ones for a lot less. I guess if you want a particular style and you can't find it anywhere else? Obviously I had a reason at one point in my life although I couldn't tell you now what it was. Have any of you ever bought a custom frame? Why did you do that and for what purpose? Just curious.