If you're thinking of making a B550 build, but struggling to comprehend the high prices, we have some good news for you. ASRock has announced a new line of A520, the successor to the A320 line and with the same modern chipset as the B550. They will be released sometime at the end of this month or in September.
One of the main proponents of the upcoming A520 line is that it is affordable. These are projected to be well under the B550's $130+. However, they may not support PCIe express 4.0. Personally, I am not very hung up about this, as my SSDs are fast enough already, but for people who work with massive files, this may be a deal breaker. Fortunately, since this is a motherboard for budget builds, this should not be a big issue. Other than those minor differences, the A520 motherboards are almost identical to B550.
These are an exciting new development, and will hopefully be the next-gen equivalents of today's B450 motherboards. I can already see a $500 Ryzen 3 A520 build!