>>776266Idk what it will be like for a fixie or road bike, but with BMX, you could spend $700 on a really nice complete bike. To build almost the same bike using individual parts at full retail, you will probably end up spending like $1100-$1400.
A BMX mailorder company called DansComp used to sell a kit with everything besides the frame so you could buy your own frame and get the kit for another $300-$500, but a lot of the major parts were mediocre in the kit and you can't really get specific sizes you want.
Just remember, those $10 bearings and cables start to add up real quick.
I mean maybe you could find a cheap used bike with shitty wheels and a couple broken things but a frame you like, then order some of the major parts like a set of wheels, good cranks, fresh grips and tires, and build it up while still having lots of the small parts like the headset and seat post that are still good from the old bike. That would be the cheapest if you really want to build it up.