The Kubota US LIST price for pn #BL8060-1, front suitcase weight, 55 lbs. was $60.00 USD as of Jan.1,2007.
Each weight requires one bolt kit pn #BL8060B at $2.00 USD per.
Using more than one weight requires a bracket to combine them. There's one bracket for three, and another for up to five additional weights. I've not seen that assembly so can't describe it.
Hope that will help.