Haven't checked your source, but attended a local gun show today.  Found one restored model 1898 bayonet. the vendor wanted $250.00 for it. It was beautifully restored, I wish the one I am currently working on had that level of care put into it. Storey was that the restorer has past on.
Several on EBAY have gone from $75.00 (very poor condition) to $210.00 (well restored). Last firearms auction I checked was asking $250.00 for a bayonet and sheath in a presentation case.
I can only speculate that a good one will enhance the value of the rifle, if you intend to sell, and probably by as much as the bayonet is really worth--some may buy the rifle just to obtain the bayonet.
As for me and mine, I believe that any military issue rifle is incomplete without one.