I dont want to keep beating a dead horse, but...
for 180 bux more than the stock HG you can have an HKS mhg...and then you take the head off yourself...bring it to a machine shop and for another couple hundred...max...you have it machined and the head rebuilt. To me, spending the extra 4-500 is worth piece of mind. Once you start getting power, you're gonna want more and as you turn the boost up, that oem gasket is gonna give at some point...
As for the other gaskets, usually you get a kit from Toyota or somewhere else...
Goodluck