LG K30 now available at Amazon as Prime Exclusive at a much lower price

The fact that it's available as a Prime Exclusive smartphone is probably the main reason the device is so much cheaper than T-Mobile's version. It's also worth mentioning that Amazon is selling the 16GB model, whereas T-Mobile's model comes with 32GB storage inside.
Specs-wise, the K30 is clearly an entry-level device, which ships with Android Nougat on board. The smartphone packs a 1.4GHz quad-core Qualcomm Snapdragon 425 processor, 2GB RAM, and 16GB expandable storage.
It also sports a 5.2-inch display with HD (720p) resolution, an 8-megapixel main camera, a secondary 5-megapixel selfie camera and a 3,000 mAh non-removable battery.
The LG K30 comes unlocked and it will work with major carriers in the United States such as AT&T, T-Mobile, and Verizon.
source: Amazon via Androidandme