You have one of the best custom rifle platforms available to you, as it is, with the 700 action and the 26" 1:10 twist heavy barrel. You could always sell the stock, sell the barrel, and build a custom off of your current action... Or just sell the stock, and put a better/different one on it.
As for the value of the rifle itself, this is simply my opinion, and I am not a professional appraiser.
Being used (if it is in-fact only 100 rounds down the barrel), but adding in the Timney trigger, I'd say it's probably worth right about what they sell for new, so $600-650'ish range. From a buyer standpoint, I probably wouldn't go more than $550-600, even with the low round-count and the Timney trigger, only because the fact of you don't know how it was broke-in, you don't know how well it was kept, how hot the barrel might have gotten if someone made long shot strings, etc... Too many unknowns in the used rifle world, and I've been burnt before.
I'm just going by what I see the value of, if I was the one interested in buying it. I always try to get the best deal, being that I only buy. I never sell. But if it were my rifle and I was selling it, I don't think getting $600 for it would be out of the question.