You are at risk of a raid from ordering any amount what-so-ever of anything illegal. You are very unlikely to be raided for personal use amounts of lowly scheduled drugs (xanax) or research chemicals or marijuana seeds. Any amounts of anything else and you are at risk of a knock and talk. I know of people who had knock and talks over ounces of weed, and were charged. If you order sheet of acid or ounce of MDMA I wouldn't be surprised if you are raided either.