TheFork users who ate in Cartagena have said really good things about The Curyy Corner, La rachola and La Casa de Papel. Maybe you should give them a try!
Some of the more popular Cheap eats restaurants to eat on budget in Cartagena according to TheFork users include:
The Curyy Corner, with a 9.3 rating
La rachola, with a 8.8 rating
La Casa de Papel, with a 9 rating