Franz Krump just sold his blue targa to a young fellow in Monaco, I think, and then he bought it back. He also bought one of Kjell Jansson's. Those are the only recent sales I can think of off-hand. I don't know what the prices were, and I don't think it would be polite to ask, but I will ask them both for a general answer to your question. They would know better than anyone, being totally immersed in the 90 Si and having tracked all the known cars for many years.
My overall impression from advertised asking prices over the last couple of years is that prices have been going up steeply, and finding one for $150k USD would be difficult.
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