THey are really nice peices but I doubt they have any monetary value at all. Even football memorabilia has low value other than a few exceptional peices.
RL is not a big game and does not have too many wealthy fans. Also player signature are not all that rare.
I may be wrong but if you want a true valuation you need to get in touch wit him someone who specialises in this stuff but be prepared to be dissapointed.
You could chance your arm on e-bay, set the lowest reserve you’d accept and see if you can get a bidding wars going.