5k is a bit low but its possible It's very important to make a good elo deck from the beginning as they give you credits, clintz, and crs. It grows your collection rapidly.
Roots without noodile, Jeena, or Tuck? Without those, the deck isn't the same.
Maybe Allstars without Marina, Saki? Possible but still not that good.
Freaks without Bogdan, grudj, Akendram?? very difficult to play.
I think you should try Jungo or Junkz (both are quite cheap and easy to get the hang of)
Jean, Pegh, Mindy, Scopica, Rodney, Buba, Greow, Troompah/Ongh should work. (Benicio and Niva are also good replacements for Greow.
Eebiza, Qubik, Veenyle Cr, Dreen, Flanagan, Fuzz, Tremorh, Romana is great.
Best choice for me is mono Piranas, 5 staple cards are super cheap and used in 90% of monodecks: Puff Tula Ector Taljion Coleridge (less than 2.5k all ).
11 stars to fill with 2.5k, u can try Kristin Sheryl Tyd/Morgane, or if u want to play a 5* use Sliman and play 5-3-3.
If u prefer biclan consider ulu and Roots, u can make a decent deck without spending a lot
NICE! You actually stayed within the limits of 5k. I couldn't do that.
Puff, Coleridge, and Ector aren't used in 90* of mono decks. Coco, Hawkins is used instead of Puff. Coleridge isn't used as much as Raeth, and Tyd is used more than Ector.
If you're going Piranas, I can lend you some cash for Raeth and Dalhia Cr/Selma