How many shoes does one need?
I believe like all athletic shoes, it depends on your frequency in engaging in the athletic activity.
For example, I played badminton about 3 times a week, so I purchased 3 pairs of badminton shoes, which I used regularly.
3 shoes in rotation for the 3 days. This has allowed me to wear the shoes for at least 2 years.
i.e. a $100 pair shoes ÷ 24 months = $4.2 per month spent.
$4.2 x 3 = $12.6 spent per month for badminton shoes.
After 2 years, the glue degrades, the outer soles wears out and the shoes fall apart...
Welted leather shoes (unlike glued shoes) on the other hand, can last up to 20 years when maintained properly. So far, no badminton shoes are welted, i.e. can be resoled.