I've had my prices at 50k apiece for a really long time, and I feel like it's time for a change. What would you guys recommend that I charge for a base price?

I would suggest going up to 75k

I'd go to 65k. Don't want to knock them up to much just in case you were to lose some business due to making it 25k more than usual. I'd also charge an extra 10k for special markings such as the eye on the second piece and 15-20k for fantasy elements if you do them. Very lovely work :)