Are expensive air filters worth the extra cost?
They certainly are! As the saying goes, "you get what you pay for".
Here is a rhetorical question, how much is your health worth? The cheapest filters, like fiberglass filters, are made to keep really large particles, like roaches, from getting into your system's blower or fan. On the other hand, a MERV 13, five inch deep air filter will protect your health by capturing many microscopic contaminants and pollutants, such as pollen, cat and dog dander, microscopic dust particles, dust mite parts, mildew, mold, Covid carrying particles, and many more contaminants and pollutants.
So yes, the better, more expensive filters are worth the extra cost.