Generally, the two-product 50/50 simulation approach (with and without product enhancement) overstates the WTP. We would recommend running simulations with a more realistic set of competitors and the None alternative (say, 5 or so total products plus the None). Then, simulate the WTP product (the product for which we'll be estimating WTP) without the product enhancement. Write down its share of preference (perhaps it is 15%). Now, enhance that WTP product with a change to one of its attribute levels. Next, find the change in price that drives the share back to the target original amount (15% in this example). This approach gives a more realistic and lower WTP than the 2-product approach.
And, yes, it does matter what price you start simulating the base case at for the WTP product. And, it also matters for your 50/50 two product case (unless you've fit a purely linear term to the price attribute across its continuum).
Its typical to have 200 or more respondents for CBC, when you are trying to project to universes of 500 or more consumers. So, 100 is a bit small. But, your results are probably much better than a guess (without any data), so there could be value even with small sample sizes.