I’d stick with new kites. If funds are tight, just buy new kites either on clearance, or from one of the direct-to-consumer outfits like switch. These days there is very little difference between brands and across years. Canrinha is no better than any other brand, just shop around.
When buying used, you never know what longevity will be, even if the kite design is good. Once you are pretty familiar with kites, you know what a worn out kite looks like, and buying used gets less sketchy, but you’ll still never know what you are getting.