Disregarding the signature:
The Predator sneaky butt without the shaft is probably worth $50 to someone that has a 314 shaft already.
Including the signature:
Signatures in general seem to have little affect on the value of pool cues. Some players might pay a bit more, but some may pay a bit less, so it evens out.
In this case since it’s not a fancy butt, maybe it would increase the value slightly.
Imo, and we all have one