well to me i don't think low price means unhealthy ,actually there is also some clothes once are very expensive but if you buy them at different seasons the price will be vary .for example ,how do you think if you buy a T-shirt in the winter ?of course the price will be much lower than that in summer .so you see the same clothes does not mean the same price ,that's why you can identify a clothes on its price .you should think more is the quality .as you said the clothes is for child .i think you should consider the material first . some material may not suit for child as child's skin is easily be hurt .you should choose some wild material like something made of cotton
a good quality is the first thing you should consider first while purchasing cheap racing swimsuits ,you must made the quality match your price