China’s legendary black markets have goods and services for every need, from organs to counterfeit designer handbags. For cashed-strapped Apple fans in this communist country, there’s also a thriving market around iPhone upgrades.

For as little as $100 U.S. dollars, the 16GB iPhone can get upgraded to 126GB. That’s a big deal to Chinese consumers, who have trouble affording the 16GB iPhone 6 at just over $700, let alone any models with more capacity.

The back-alley upgrades were reported in China Realtime, a blog of The Wall Street Journal. From online services to sidewalk shops, iPhone users can find repair vendors that will happily swap out memory chips.

China is the world’s largest smartphone market and Apple is aggressively going after a slice of the pie there. During recent earnings reports, Apple reported a 112 percent increase in iPhone sales in China over the last year. Forty percent of all iPhone sales last quarter came from China.

Apple, as you can imagine, frowns upon such tampering. Industrious mobile repair technicians have found workarounds that let them clone contents and serial numbers onto the new chip. The swap can only be made after a user has registered their serial number with Apple.

Any unauthorized service on smartphones is fraught with risk and will obviously void warranties. China Realtime reported the upgrade renders some parts of Apple’s iCloud service unusable.

For now, the repairs can only be done on an iPhone 6 and not a 6 Plus, according to the website SlashGear, which featured a series of photos off Imgur from one shop showing how the chip is replaced.

Source: China Realtime and SlashGear