Nokia 3.1 and the Nokia 5.1 here in India are down to Rs9,355 and Rs11,899 respectively. The former smartphone also got the Android Oreo 8.1 update a few months back which means that even the device is a bit old you are close in getting the latest Android version. On the other hand, 5.1 comes with the Android 8 out of the box.
Buy Nokia 3.1(Flipkart) | Buy Nokia 5.1(Amazon)
Inside the Nokia 3.1, you have Octa-core MediaTek 6750 processor clocked at 1.25 GHz, 2GB/3GB of RAM and 16GB of storage, 13MP camera, 2990 mAh battery, 3.5 mm headphone jack. For detailed specs, check out the complete 3.1 specifications.
Nokia 5.1 has an Octa-Core MediaTek Helia P18 coupled with 3GB of RAM and 32GB of secondary memory for storage. There is also a model with 2GB of RAM and 16GB of storage. The device also takes some great photos with the 16MP rear camera and an 8MP front camera. You can take a look at the full spec sheet just by clicking on this link.