It's going to be a lot cheaper to buy a complete.
The Cygnus is a cruiser (24") which might actually be ok for you because it sounds like you might want to use it more for a commute than a BMX bike. But the DK Helio is a great starter bike for the price. Best bang for your buck.
You probably don't need the gyro on the Convex, and the Blackeye is more than your range and it's a scooter. That frame is sooo ugly.