I just recently did this. The radio was $89 and had the fewest features I could find: CD, USB, aux, am/FM and NO Bluetooth or touch screen which exactly fit my requirements. It's replaced my terrible touchscreen system and given me 2 single din slots of storage space. Replacement was relatively easy and as long as you have a headphone jack on your phone, there are no issues. Just need a soldering iron, removal kit, car-specific mounting kit, and model-specific wiring harness.

Of course, it's much easier to find one with Bluetooth; there are tons of other ones with "smart" features that are the same price.