This does sound very high.
I know that a four wheel alignment on a Porsche at an official Porshe dealership, which takes 2 hours min and aligns all four wheels for camber, caster etc and requires details like driver seat weight added, cost's less than that, so I would be tempted to shop around. This isn't rocket science after all.

I know that a four wheel alignment on a Porsche at an official Porshe dealership, which takes 2 hours min and aligns all four wheels for camber, caster etc and requires details like driver seat weight added, cost's less than that, so I would be tempted to shop around. This isn't rocket science after all.