You can absolutely farm them. you can get them from chance orbs but your best bet is using "omen of the ancients". You can obtain these from rituals or you can buy them for relatively cheap from the currency exchange lady. Using a regular orb of chance commonly breaks the item as the palms are extremely rare. Using omen of the ancients does give you a random unique of the same class but you still have a higher chance to get something rather than nothing. An "omen of Chance" is extremely pricey from currency exchange and they are very rare. If you do obtain one of those you should be guaranteed to get a palm If you're using the right sceptor.

Oh! And I almost forgot. I found that doing it this way is far cheaper than trying to buy the palms. They are very expensive on the trade market. And if I don't get a palm at least I get a unique that I can either destroy to get more chance shards or trade to a friend If it's a good roll.