I honestly don't think guiacol is needed for 200mg/ml prop. But don't put too much trust in that recipe being painless. That's a lot of hormone per ml when dealing with short esters. You can get guiacol any place you'd get your solvents. Guiacol will stink up your place for weeks, you sweat it out yours pores, it's very unpleasant but is needed for no esterd hormones. Good luck.