If you arent playing for a long time now on your current server I'd recommend switching to one which suits your timezone more, since missing 5k sun scrolls every week is a lot of waste, not to mention literally every single evening event.

To answer your question konoha gift shop, treasure of the sages, konoha outlets usually have optional scroll pack with 30 elemental scroll of your choice for 1.5k cp. Training grounds offer up to 2 random scrolls for killing guardians at higher floors. Fukurokumaru deals, recharge spend events usually have 30scroll packs as well. There are also single scrolls (random unfortunately) available in most events, either on lucky board's board, some events like balloons or time limited shop.