A client of mine had the issue and he ended up setting shipping cost by weight for larger spans beyond a certain point in order to simplify the shippingcost maintenance in the long run.
So some of his customers who buy like 200kg will pay the same as those who buy 230kg and hence pay a little xtra where those who buy 230kg pay a little less for the shipping, so it evens out pretty good for my client and in regard of the customers, well if they buy such large amounts of good from him, it doesnt really matter whether the shipping is 15 EUR more or less. :-)
So some of his customers who buy like 200kg will pay the same as those who buy 230kg and hence pay a little xtra where those who buy 230kg pay a little less for the shipping, so it evens out pretty good for my client and in regard of the customers, well if they buy such large amounts of good from him, it doesnt really matter whether the shipping is 15 EUR more or less. :-)