Not trying to insult. It's just obvious that you're one of many who have a wild misconception about industrial and electronic design costs. Seriously, billions?
Heck, insiders have said that the entire original iPhone project only took $150 million, and that included 100 engineering, support staff, and programmers for a year and a half, plus custom test facilities. All done with a team with zero cellular experience.
The Watch, which apparently also got 100 people assigned to it over about the same time period, would be technically easy in comparison. No cellular involved nor anything else special or that new. Cases could be made in any quantity by existing factories, as could all the straps and the internal electronic parts.
And yeah, many have used much less money on Kickstarter to hire Chinese factories to build their devices.
Now, granted, maybe Ive spends billions making thousands of mockups

. He's lucky he had Jobs on his side. The places I've worked at would've fired him for being such a bad designer that he couldn't come up with the right design a lot sooner