I agree the mercury seems very expensive, but sounds very nice. I’m surprised it’s so much more than the redstone. I asked Spaceman and they were very helpful and this is how they compared.
Saturn - Simple, great harmonic profile, stacks great with just about anything, leaner in the lows.
Redstone - More tone shaping, burlier when driving or driven, more and thicker especially in the lows, more gain overall.
I’m thinking my preference is Mercury>Saturn > redstone. So I may go for a Saturn since it’s available and cheaper than the redstone.