SHENZHEN, China \u2014 Between baskets filled with hard drives, memory sticks, LED lights and countless other bits of technology hardware, Jason Gui found what he was looking for: a handful of tiny batteries.His business partner, Tiantian Zhang, whipped out her phone to pay for them via WeChat, the all-in-one messaging and payments app ubiquitous in China, and transferred about 4 yuan, or $0.60, for each battery.The bustling wholesale market with its rows of vendors is part of Huaqiangbei, a subdistrict in the Chinese city of Shenzhen that has become known as the \u201cSilicon Valley of hardware.\u201dFor Gui, it\u2019s better than that.Silicon Valley was \u201ca little bit slow for us,\u201d Gui said over his workstation at Hax, a startup incubator in Shenzhen. \u201cIf you were to do this in the U.S., you would just be importing the same materials from China anyway.\u201dGui, 28, and Zhang, 30, are known as \u201chaigui,\u201d or sea turtles, a term for foreign-educated Chinese people who have returned to China.About 80 percent of Chinese students who get degrees abroad now go back \u2014 up from about 33 percent in 2007, according to China\u2019s Ministry of Education. Some 15 percent take jobs in China\u2019s booming tech sector.That has implications for the United States, with experts worrying that as China turns more attractive for talent, the U.S. will lose out.\u201cIf there are talented people who would be willing to stay, we need to keep them,\u201d said James Lewis of the Center for Strategic and International Studies, a Washington think tank.Lewis added that uncertainty over immigration has made that harder, just as China \u201chas put a huge effort into enticing these students back.\u201dFrom Silicon Valley to ShenzhenGui and Zhang returned to China to start their company, Vue, after graduating from the University of Pennsylvania in 2013. Along with an American co-founder, Aaron Rowley, they make smart glasses that track wearers\u2019 activities and connect to their smartphones to play music and accept calls. Cheap and ample products make it possible for them to iterate quickly, turning a prototype into a finished product in a matter of days.Gui and Zhang initially moved to San Francisco after graduation. But they accomplished less in a year there than they did in a three-month trip to Shenzhen.Gui\u2019s and Zhang\u2019s office sits just upstairs from the sprawling market, and their factory is an hour\u2019s drive away. That proximity has saved them time and money, and the pace is faster in Shenzhen, Gui said.\u201cPeople work really hard until really late,\u201d he said.More on MSNBC\u2019s \u201cOn Assignment with Richard Engel\u201d Made in China Sunday at 10 p.m. ETChina\u2019s tech sector has its own shorthand to describe the hours that employees work in the country: \u201c9-9-6,\u201d meaning from 9 a.m. to 9 p.m., six days a week.\u201cOur factories are still talking to us at 10 p.m. or 11 p.m., sometimes well into midnight. They\u2019re working on weekends, so things get done much faster,\u201d Gui said. \u201cWhereas back in San Francisco, after 5 p.m. people won\u2019t respond to your emails and you can\u2019t get anything done until the next day.\u201d\u201cYou can\u2019t do that in the Valley.\u201dChina\u2019s startup scene also offers entrepreneurs the chance to do more with their funding, thanks to lower resources and labor costs.Wang Meng Qiu, a startup founder who graduated from Stanford University with a doctorate in computer science, held jobs at Facebook and Twitter in Silicon Valley before he moved to the outskirts of Shanghai to launch his own drone company, Zero Zero Robotics.Wang said the salaries of his 40-person team for two years cost $700,000.\u201cYou can\u2019t do that in the Valley,\u201d he said.The pay discrepancy between Silicon Valley and China has narrowed since he launched in 2014, especially at top-tier firms. Wang\u2019s engineers now make 70 percent to 80 percent of what they could get in America.That has helped him poach other U.S.-educated engineers. A decade ago, if you were a computer science whiz, \u201cthe only place you could make a good buck was in the U.S.,\u201d Wang said. \u201cBut now Chinese companies are making comparative or even more attractive offers than those in America.\u201dIf he had wanted to pursue a career in academia, Wang said he would have stayed in America. But to build products and achieve commercial success, China\u2019s know-how, available capital and massive consumer base won out.\u201cWe\u2019re not as fast in fundamental research or core innovations. But in the area of technology application, I think we\u2019re actually leading the world,\u201d he said, referring to Chinese advances in e-commerce, messaging and mobile payments.Market fitA similar rationale guided Wang Yi, who graduated from Princeton University with a doctorate in computer science in 2009. After a stint at Google in San Francisco, he got the itch to build his own software product: an app for language learners that offers personalized instruction.Wang said he wanted a \u201chuge market\u201d and proven user demand. China fit the bill \u2014 its middle class is expected to reach 550 million by 2022, according to consulting company McKinsey. The share of per-capita education spending among Chinese 20-year-olds is about twice that in the U.S.Yi now lives in Shanghai and runs LingoChamp, or Liulishuo, the app he launched in 2012 with two other Silicon Valley expats. It claims to be the world\u2019s largest bank of Chinese speakers, with more than 80 million registered users.Operating in China hasn\u2019t stopped Yi from wanting to build a presence in America. LingoChamp went public on the New York Stock Exchange last year. The same goes for Wang of Zero Zero Robotics \u2014 half of the company\u2019s orders come from America.But Wang said he\u2019s in no rush to move back.\u201cChina just offers more opportunities,\u201d he said.