The rules for using Bio/Cyber tech relates to the repair, maintenance, and installation of that kind of 'ware. Usually, you'll see Street Docs having a large amount of medical, then some Cybertech or Biotech on their skill list, listing how good they are at transplanting and inserting them.
For building that kind of stuff, that's a lot trickier. What you're looking for is a plethora of things. Remember that corporations keep very heavy tabs on their intellectual property and their human resources that can do that kind of stuff. Think about an extraction mission you might have done at one point. That egg-head your team was protecting or bagging to deliver to another company was a single researcher that lends his knowledge and skills to creating one portion of Bio/Cyber ware. For Cybertechnology, you need knowledge of material fabrication and technology, biology, neurology, phisiology, chemistry, physics, and a number of other smaller skills. And that's just to create something that's intended to be used as cyberware. Then there's the computer technology aspect, where you'd need high-end data programmers, IT specialists, Matrix specialists, and groups of scripters to actually write the code that the computer engineers create.
When you think of a wage slave or scientist in these settings, those are the people you're thinking of. And that's just to create this one thing that you're looking for. That's not even taking into account all of the logistics that go into running things. Oh, and don't forget the amount of resources needed. You'd need raw parts, fabrication machines, lab equipment, clean rooms, a surgical theater...and that's if you want everything done right.
The process to make, maintain, and upgrade this stuff is extensive. To install it is pretty easy, in comparison, since once it's been created, you just hook it up and calibrate it. That's why you see such large price tags for this stuff. Now, in retrospect, this stuff isn't as expensive as it could be, but that's because of technology for mass production pushing down the costs, and military contracts doing most of the heavy lifting for the research and development aspects, letting the corporations shell off the non-military grade stuff to consumers on the streets and security companies.
And that's not even getting into Bioware, which takes more in certain skills and such to be effectively grown.
This is why you don't see skills being used to build this stuff. It's frag'n complicated. Just do what any sensible Shadowrunner does and steal it. :P