1) Figure out what kind of panel you want.
2) Decide if there are any specific features you want/need
3) Find those for the cheapest price.
4) Determine what the best source for your needs is (Likely this is going to be an Amazon Fire Stick on the low end, an Nvidia Shield on the higher end, or a Raspberry Pi for the DIY crowd)
You can usually find a really good panel for a really cheap price from Vizio or TCL. I think TCL recently started making their own panels? So, you might not be getting a lower-binned Samsung/LG panel anymore. TCL also has Roku software built in, if you're looking for a budget option.