Now let's see:
"...costs go up by approx. the 3rd power..." add: of the length. For the same type of boat
goes up with the third power of the length: so a boat
twice as long will weigh abt 8 times as much & cost about 8 times as much (2³=8)
While this is an extremely rough formula, it is not sooo far out. Of course not when comparing a HR with a Bavaria
or a Swan with a Hanse, or if comparing a 5 year old boat with a thirty year old one.
This means when you take a certain size-bracket into consideration while having a fixed budget
& pretty close ideas of the age of the boat that you are looking for "42-50" is much too large a bracket, as the 50 footer will cost approx(!!!) 1,68 times as much as the 42 footer (50/42=1,19 and 1,19³=1,68), again comparing same style & age of boat. This pretty much applies to the purchase
& the refit
costs & is of course a VERY rough approximation.
What I want to lead up to: 40'-42' or "48-50" would be a sensible bracket, & if your first idea is "42-50" you should read up on prices & about the huge difference in upkeep & running costs between a 42 & a 50' boat.
Of course you will find 42'ers for the same price
as 50'ers on the market, but they will hardly be the "same type" & "everything else the same" - boats.