No, IMO it would be a Bechinah of קנאת סופרים תרבה חכמה.....
I strongly disagree. It would be tragic if people who can in no way afford to spend $250 on arba minim felt like they had to because of peer pressure.
Besides for the lack of modesty in bragging about how expensive your esrog is...
#myhumbleopinion
As for kinas sofrim tarbeh chochmah, that is referring to learning torah/knowledge of torah. Perhaps one can extend it to other mitzvos, but how much you paid for a mitzvah is very different than how well you performed the mitzvah. How much kavana did you have? How precise were you with the halachos involved? On that one can say kinas sofrim tarbeh chochma, perhaps. But not on the price you paid. Absolutely not.