Hi musteq,
There are many things that can contribute to the temperature regulation of a mattress and all the different influences and “layers” tend to work together … including of course the bedding and blankets. There is more about this in post #2 here and post #29 here.
If you do decide that the comforter is the culprit … then wool can make a great temperature regulator because of it’s ability to ventilate and keep moisture away from the body. there’s more about this in post #6 here.
Besides the normal range of prices that comes from different businesses with different cost structures, sources, and profit margins … the cost of a wool product will be connected with the amount of wool in the product, the type or breed of wool used, how it is treated and processed, other fibers used in addition to wool (such as the cheaper polyester used in this one for example), the cost and quality of the other materials or cover around the wool, the type and quality of the construction (quilted, baffled, tufted etc), and even the labor costs in the country of origin.
Some of the better sources I’m aware of for wool bedding products are listed in post #3 here. While this is more about wool mattress pads and toppers … many of the manufacturers listed also make wool comforters.
As in all mattress and bedding purchases … who you buy from and their ability to inform and educate you about the benifits of the different materials they use and products they sell so you can make more meaningful choices can be just as important as what you buy.
Phoenix