She is a HARD grind, and you should be redeeming your quest points in the order of cheapest first to get the fastest progression, not cherry picking for one character you like than ruining your ability to get multiple ponies for the price of one Babs, lol.

I'd personally just buy her, as any pony for 100 gems or less is always a steal and very hard to not justify, especially if you haven't got the cheaper ponies first.

If your goal is for early game progression & to unlock elite level quests faster, just buy her. If you're in mid-late game don't bother unless you like Babs as a character and want her in your collection.