I didn't want to pay the big bucks on a prebuilt one, so I made plans and built two so far for myself. I'm able to get a reasonable price on aluminum stock through work, but the total for all the materials still comes out to about $350 if you're using the large 21" smooth tires. Luckily it only takes a couple slow days at work to cut and weld them together. You can get the price down to $275 if you get 18" tires. Bonus is you've got more durable tires and tubes, and steel rims with bearings that won't shatter when you bounce off of something hard.
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