New - used? What is it's real value at the time you paid $150k? And it does matter what brand boat mfg - some lose their value much slower than others.
How's the economy in 10 years? Clearly, this is un-answerable for no other reason than the economy, as we all know these days, has a significant influence on boat prices.
Probably the only accurate answer you can expect is - it cost what it costs.
For all the permutations of this question, I guess some will continue to plug numbers into spreadsheets in a valiant attempt at answering the impossible to know.