"¿Cuánto cuestan las botas rojas?"
Translation:How much do the red boots cost?
A native speaker would understand you ... and think "She must be learning English." Many questions in English require the "do, does" construction. WRONG Likes he rare steak? CORRECT Does he like rare steak? WRONG Have I to pay now? CORRECT Do I have to pay now? This is a unique feature of English, whether British, American, or international. Thus, it is useful to learn and use.