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It usually seems people justify the cost because they spent the money on it. As long as it's got the same zippers, the same stitching and the same materials and thickness, there is no difference in protection between a $2500 suit and a $200 suit. Now you have to actually look at the product. There are some full length motorcycle sport boots that don't have any hard plastic parts like $300 boots, but there are $75-$100 boots that do have the hard plastic parts. Don't get the $50 soft boots, do get the $75 hard plastic boots. Only get the $300 boots if you want to spend money and look cool, but they don't protect better.
I've crash tested my $15 back protector, $20 gloves, $70 boots, $350 suit and $75 helmet 3 times on the track with 0 injuries. The stitching on the gloves eventually started to loosen up and they got holes worn in them after continued use so those have been retired for another set of $20 gloves. The screws that held on the hard plastic parts to the boots snapped on the last crash on the boots and the soles got a gash in it that went half way into the material so those have also been retired. The boots were replaced with $150 boots because they are also waterproof otherwise it would have been $100 boots. The helmet has also been retired as it should after a crash no matter how expensive. Since helmets have standard safety ratings and materials you are guaranteed the same protection in a $75-$150(fiberglass shell, snell 2010) helmet as a $1000 helmet.