This is the 8081st most frequent Catalan word.
costi
"Costi" is the third-person singular present subjunctive form of "costar," meaning "it may cost" in English.
Here, 'costi' is the present subjunctive form used to express a condition or uncertainty regarding the cost.
No importa quant costi, compraré aquest llibre.
It doesn't matter how much it costs, I will buy this book.
In this sentence, 'costi' is used in the subjunctive to convey a desired outcome regarding the time it takes.
Vull que costi menys temps preparar el sopar.
I want it to take less time to prepare dinner.
In this instance, 'que costi el que costi' is an idiomatic expression that emphasizes determination irrespective of cost.