Supposedly the prices for RPi have gone up over the past little while, because of supply problems. I've been using B4A/B4J for years off and on, and I'll take Erel's advice and wait for a half decent price for RPi 4. At least now I know what the difference is between the two models. I'm not in an immediate rush for it. Thanks guys.
I got a laugh today when I found out the RPi 4 with 4GB initially sold for $55. Now it's well over double that. I should have bought RPis instead of investing in First Horizon bank stock. ROFL
I broke down and bought a RPi 4 today just to play with. Should be fun.
I'm looking for a micro SD memory card to get for the RPi 4 and stumbled upon What’s the Best Micro SD Card for Raspberry Pi? (benchmark). I put the link here in case it helps someone else. I'll end up getting a Class 10 from either SanDisk or Samsung. Probably 64GB if they're not too expensive. The write speeds on the SanDisk Extreme is impressive. I'll likely end up getting something slower (cheaper) for now.
I have a pretty complex B4J UI app running on a RPI Zero and it's been running flawlessly for several years. A bit slow to load, but once it loads I can't tell the difference between the Zero and it's big brothers. So I would say either one would be fine but it would depend on your application and it's requirements.