"Don't spend a lot of money there."
Translation:Mai hoʻolilo nui i ke kālā ma laila.
Yes, nui can modify kālā, to mean "lots of money" or "big money." I see what you are saying, "Don't spend the big bucks there."
How about trying Mai pono lū i ke kālā nui ma'ō. Roughly "Don't just spread big dollars over there."
Mai pono lū = Do not carelessly spend
ke kālā nui = the big dollars
ma‘o = over there.
I like Lū because it implies recklessness. HA! So much fun. Cheers.