The wastegate is the last part you want to cheap out on. It only takes one failure to hurt an engine.

 

Wastegates are for sissy-boys

 

Like others have said. You don't want to use a cheap part in that area.
I havevan eBay gate here. Use it for mock up. That's it.
The valve is rusted inside. I would recommend using a hi quality part in that area.