Ken...and others:

Great questions. I expected nothing less. I apologize for not answering sooner (or being on the forums at all) but I've been fighting a very nasty virus (on my second Z-pack).
When ordering a B-25 or N-25 handle (Model #25 handle...leather/stag/leather...with either brass or nickel silver & alumin hardware) there is "no upcharge" to replace the stag centerpiece with any "shop-supplied" handle material. For example: Maple instead of stag. If, on the other hand, you wish to use "CW" (customer-supplied material) the upcharge is $20.00. Rule of thumb would be: If the Randall knife comes standard with "stag" then any replacement of that stag with something else will fall under this rule. To the best of my knowledge there are no exceptions.
Please remember that this "only" means the center when referring to the #25 styled handle. You cannot substitute the "3-piece" configuration with a "one piece, full length, piece of handle material.

"Teardrop" shaped handles are available on Randall models with blade lengths 6" and "less". There is no upcharge for this fine handle shape. In my opion (and that's all it is) folks should be careful when ordering this handle option as it may not look or work great of all models. Just as a "for instance" I have seen it on a Model #11-3 1/4" and (for me) it made the handle too long for the blade length.

"Butt caps" on a "teardrop" are limited to brass or duralumin and "not" nickel silver. "Collars" are still doable with a teardrop. Hope this helps...and, again, sorry for the delayed response. (Now I'm gonna go take another handful of pills and feel sorry for myself)...
Best, Capt. Chris

Below are a couple of examples of teardrop handles done right! A matching pair of "Stanaback Specials" and a pair of "Pathfinders" that we built on the hunting forums...CCS