Light, cheap, durable. Pick two.

OP, why don't you go into business building these bikes and selling them for $5k? You're making a grand per bike, while still undercutting named manufacturers by more than half.

Now think about warrantying them- well, that's going to take some money saved up, now isn't it?
How are you going to distribute them? I'll venture that takes money.
You going to sell them yourself, or franchise in a dealer network? Takes money to hire sales reps.
What about getting the word out, sponsorship, advertising, or manufacturer incentives? Yup, you guessed it, more money!
Now think about the scope of your brand, will you remain a boutique maker or will you create a line of models? R&D costs money, and the lower end has an even worse [sometimes breaking even or worse] margin than the halo bikes.
What about sourcing the latest and greatest? Going to take prestige (created through marketing money) or straight cash in the form of large orders to parts suppliers to get noticed. Plus, ebay and LBS deals come in lots of at most ten- trying to create a consistent product from an inconsistent input stream seems like a fool's errand.

There are a ton more, but I'm getting depressed about finally thinking through the logistics of my dream career, and you get the point anyway.