Currently: I would add in Klaws, Elke, Mok and flip Kersten with Ksendra (you don't need 2 psn cards in a GHEIST deck).

Personally: I recommend you experiment with Platinum, Mini Mund, Ernst, Gork and Ludmilla to see if you like them. (Platinum to replace Darth, Ludmilla to replace a banned Dolly, Ernst to Dr. Saw (if star level gets too high), Gork for raw pwr and dmg and Mini Mund is more of a personal preference).

Future:I would also aim to get Bristone, Z3r0 D34d and Leviatonn.

If you're looking for cost-effective elo decks, I'd strongly reccomend switching to sents or Rescue.

Save for Bristone and Wardom

Hey, Darth is good. Super-bad against about 3/4 of the cards with their bonus active, but 6 damage makes him a very good noob card, also very good if you are skilled at making perfects.
I don't like GHEIST right now, too weak. Perhaps you could try a half deck with like anything but Rescue and Roots. Look at the clans with good commons and play the newly added duel mode to get a few clintz daily.

Ever since Draheera got banned GHEIST aren't as good in mono any more.
A cheap half deck I can think of that isn't too bad will have Mok/Elke, Ksendra, Dolly and Ernst/Luba. Change Ernst/Lubra to Bristone if you can afford to, and you have a 13* half.

@Ambre

Dolly is perma banned.

I suppose the best 3* to use would probably be Luba and Klawz, or else you could for the 12* half with Mok, Elke, Ksendra and Klawz and save for Bristone, Z3r0 D34d, possibly XU52? and Leviatonn for the decent 13* half.

In my opinion, you should start with Bristone, Levia, Zero and then XU52.

Honestly, GHEIST is just a little expensive to be good and hard for starters to build a full deck.

and, DON'T BUY Klawz! BUY Ksendra !!

Now we can talk, a lot of cards you have are pretty situational, so we try to get something more stable.
Ksendra is a good start. Luba is not too bad, or Darth, so keep one of them should be fine.
Mok is a good 2 star, and I suggest add in Wurmhol for cheap defense and mind gaming.

Now you have a fine 12-star half-deck. You can sell Dr Saw and Kersten to get much better cards than that, or keep using them try to build a full deck which I don't recommend.

Good cheap other half choice:
Frozen with Eliska: buy Elke, Eliska, Hakunak, Tilmpah and a cheap 2-star. Use revenge.
Pussycat. buy Leela instead of Ksendra and use Dr Saw with a lot of dr in hand!
Freaks: Quasichoco and Varoslav.