I paid just over $360 for the 46" bercomac blade, two 42 lb weights, rear weight bracket and a set of chains in 2003 for my L120. The bercomac blade was priced under the OEM JD blade at the time, so kinda figuring he is asking retail price for what he paid for his blade and the chains (if it is an OEM JD blade ), and I see you are in Canada, so the price may be about right.
Far as the weights ?, they help with traction in snow plowing along with the chains, especially if you get alot of snow and icy conditions :rauch10: