HK416/Klukay is Overhyped
This post isn't meant to shit on HK416/Klukay. It just seems that many people, especially F2P players, are trying to save for her just because she is meta in CN. Yes, she can steamroll all content, but that's with her V3-V6. Without V3, she's still very good as a grenadier but not as effective as a boss killer (still decent as DPS). A lot of SKKs want her simply because we know Klukay from GFL1, and she's one of the main cast members.
From a F2P standpoint, it doesn't seem logical to put all your eggs in one basket for Klukai. Hell, I'll say that getting multiple duplicates of any limited character seems unrealistic if you're F2P. You'll end up needing at least 2 teams for weekly bosses and guild bosses, and some content will even require 3 teams. A cheaper alternative meta would be Vector. Vector can amplify Qiongjiu (SSR from the standard banner) and Sharkry (the best SR DPS). But, if you really likes Klukay, then go ahead and pull/save for her.
What I'm trying to say is, just pull for Dolls that you like. Don't be tied down by tier lists or META too much; just use them as a reference. One day, these META characters are going to be outclassed sooner or later anyway.