Yep, value is subjective. If all people agreeed money was worthless pieces of paper, or bits, then by definition they wouldn't be worth anything. I might pay that for a cap but not more.
That's obviously not just any cap. By wearing that cap, you're making a solid statement. Other geeks would look up to you and just marvel. Also, the text is embroidered so that will be a long-lasting piece of clothing. If one has to ask if that cap is worth the expense, then one is obviously not worthy enough to wear that cap.