French contract took 4 years to be negotiated, the US one less than 6 months, in total secret with no public check… expect big surprises at the end, US weapons program are not known to never overrun their costs
Seawolf was cancelled and only three units were built, causing R&D costs to be spread across those three units, raising unit price.
It was cancelled because it was expensive, but it was ordered during the end of the cold war and was radically more capable than the class it was meant to replace. This cost was acceptable at time of order, but then subject to budget cuts after the USSR collapsed. This raised the per-unit cost, but lowered the overall cost.
The eventual replacement (Virginia) ended up being more evolutionary from the previous class (not from Seawolf) than revolutionary, but much cheaper.
My source is having been on all three classes of submarine.