pricing are not as good as some are almost the same price as the pi 4. Are you installing retropie on them? That is the most common reason why others are still looking at a Pi 3 b+. Here is one.

EDIT: not sure if that is a good price as It has been a while since I got mine. All my new ones are now 4s. My emulation setup is an odriod xu4 and an old i5 6500 for newer sytems.