saiyuke,
Hey bro, for option 3 there r few way to do it... Of cause custom made is 1 of them... Some opt to custom their ori manifold to add another 'outlet' onto it for de wastegate or u can totally custom a new manifold for wastegate purpose... But make sure its with good workmanship in order to avoid hassle later on... Else u got to buy after mkt manifold tht comes with wastegate 'outlet'... Am not too sure for ori turbo there wil b any available, but after mkt turbo sure got...
Price me not too sure as u may hv to ask other members as i know v hv got few who r with such set up for their cars... Me onli using actuator!!!! Haha...
Cheers!!!