i just replaced mine and it was around 150 swiss francs so about US$135.

it took me about 3, maybe 4 hours to do it myself. an experienced mechanic should easily be able to do it in 2. it's not that difficult if you're used to working on cars. maybe a 7 on a scale of 1 to 10.

the dealer's diagnosis is reasonable since apparently these actuators get gunked up with dirt and grime causing them to get sticky. the parts guy at the dealer said that sometimes they take them apart and clean them and lube them and they work fine (for a while.)