With the cost reductions you mentioned, it felt to me like 50 merits kept pace with the purchasing power tip missions had in the old days, but 20 merits puts us behind where we were.
That's pretty much exactly what the 50 merits per alignment mission did. On Live, one alignment merit would get you most rare recipes. Some, like LotG +Recharges and uniques were two, and PvP and Purples were more expensive, but for the most part 50 merits/alignment mission was keeping pace.
If you were to skip past as much of the tip missions as possible, only defeating the mobs you had to (especially at -1, x1, no bosses), it was pretty likely you'd run out of tips. That's where buying them would come in.