I'm in love with my lenovo ThinkPad t420- screen is nice and small, battery lasts forever (I do have a fairly large battery though). I got mine for about 200 dollars refurbished on Amazon- here's a similar device:
https://www.amazon.com/Lenovo-Thinkp.../dp/B00W4AMWCI .
I did upgrade the RAM to 16 GB, but I only really touch that because I use VMs and emulators a lot. The graphics aren't incredible, but I'm sure you could either upgrade or connect to an external monitor with the 3932139 ports this machine has.