Ali express

I think albeit there are more shops on Aliexpress that sell these, there aren't that many sellers behind them: packaging is always pretty much the same. Some engines are sold without any box; in that case they come in big inflated plastic wrapping. Also, you can find them on eBay, still the more or less the same packaging, but you got the items faster; once I waited over 3 months for the Aliexpress package to arrive...