I love singlespeeds because of their simplicity; they're easier to fix (no shifters to tune), easier to spec (no money to spend on gears), and maybe even easier to ride (just pedal!). but I believe they're very personal. I don't believe that I would ever buy a singlespeed made by someone else.
At least for me.
For the kind of singlespeed that I most often dabble in - the poverty or near-poverty bike - it's much more about the accomplishment than the result. check out this Kona I put together last summer to see what I mean;
Kona humuhumu-nukunuku-a-pua'a frame with a stuck bottom bracket
4 inch riser bar
shimano XT cranks
creaky rocky mountain hybrid fork
cantilever brakes (front only)
This bike was really pretty bad. I didn't have any cable stop for the front brakes, so I tried just looping the housing over the handlebar and zip tying it down with extreme prejudice. While terrible, this was an improvement over the internally geared 3 speed coaster brake hub that was the only brake on v1.0 of this bike.
But the crank was pure genius. Because the 122mm BB wouldn't come out of the frame, and the low profile XT crank was the only 175mm crank I had, I needed to resolve an impossible chainline issue. This crank had a spider attached to the crank arm via a lock ring that the chain rings attached to. I took this off, and reversed it, so that the big ring was now well inboard of the crank arm. It looked really weird, but the chainline was near perfect.
I rode this bike for about a week, then one day I needed the post out of it to put in another frame so I could work on it on my workstand. I put the Kona outside the garage and forgot it there. The next time I went out to the garage, it was gone. Without a seatpost, or even a seatpost collar mind you.
I wasn't that choked up about it though - if i was selling this bike to someone else, I wouldn't have taken more than $40 for it. Hell, i'd have given it to any friend that was interested. The parts on it were essentially useless, the BB was only held in place on the drive side. The idea was to ride it and hope that it destroyed itself so I could somehow cut it out, and then strip and paint the frame - make something nice out of it.
The fact that someone came into my yard to take that bike was what bothered me.
(by the way, if you're out there, and there's a hell, you're headed there buddy. you better have given away a couple working bikes in your day to make up for that karma cap hit.)
I guess for me, it's more important to put the bike together than to ride it.