Balanta is a lot cheaper than Marquinhos and he turns world class. Another world class potential DC is Vallejo and he should come a lot cheaper, but you need to wait a couple of years for him to develop fully in your reserves/out on loan. Balanta can step into your starting side straight away imo.
Tin Jedvaj, Balanta, Vallejo, Munoz, Sviatachenko (2.5 mill release clause SP) Diego Reyes develops well and hes cheap theres loads plus i dont know your budget and who you are but if you have about 7mill then balanta is your guy