IMHO, it would be best not to skimp on the tablet. I've gone thru 6 or more in 3 years, searching for the best combination of size, performance, and brightness. It's next to impossible to max out all those for under $100...
Your tablet choice is your "window" to every flight you log, so you might want to choose wisely.
Start here: Best Tablets/Phones for DJI GO (Updated Daily) - Phantom Help