Just to add something to TJ Hooker's post for emphasis.
For the most part you can get into the Ryzen eco-system pretty cheap with a system you can build dreams on because of its upgradeability on the same socket. But that's not nearly so much the case with A320 boards; they ARE the cheapest but with that they generally have the worst VRM's, don't allow overclocking and have arguably the worst support for high-speed memory.
I'd suggest looking at B450 boards. There are many that cost hardly anything more than A320 and yet offer great dream potential all the way up to and including 3900X or even 3950X processors.