If you're paying $13 for a stem, there are going to be compromises somewhere. For example, the one you posted does not specify whether it is forged or cast. With Nitto you are paying for a very strong forged stem. The one you posted might be a weaker cast stem. Regardless if cast or forged, the quality control on these can't be great at $13, not something I want to gamble on with a structural component such as a stem. Also, the listed weight for a very tall Technomic with 100mm length is 304 grams. The weight listed for the one you posted is 314 grams, and that's an 80mm long stem that is not as tall as the Technomic. Another casualty of the price.

You can get a brand new Technomic for $35. Or you can go on eBay and get a used one for $20-25. I think the extra $10 is well worth the quality.