You can get them from the shop for 2000 contribution points. You can redeem them from events like lucky board, luck stars, etc. You c*so just buy them directly for I think 20 coupons or higher than that.

If you are speaking about adv refines, the best events are shinobi feast and treasure of the sage, where you can get them at 25/refine and 24/refine (if you get 40% discout, a 30% could let you buy them at 27/refine which is still somewhat acceptable). Mostly other places are *a recycle bin* (why is tr4sh censored? Lol), since you will find yourself buying them at 30+/refine.

based on experience, the best way to get refinement runes (regardless which type you are looking for) is from events that offer a discount. I find Lucky Board that appears usually near the beginning or end of the month to offer one of the better rewards.

~Jib

Im looking for medium and adv refine

If you need it right now and cannot wait, then I would say the "Konoha Outlet" event on April 3rd:

If you can wait though, I would say wait for the next Lucky Board, Treasure of Sage, or Purchase Limit Shop found in the "Shop" in the bottom right hand corner.

~Jib