Well, some libraries have manga collections that you can borrow for free. That's a cost-effective option. Also, keep an eye on sales and discounts on major online bookstores during special occasions.
Check out local comic conventions or manga swap meets. You might find people selling manga at reasonable prices there. Also, keep an eye on sales and promotions on official manga websites.
Library sales or comic conventions often offer discounted comics. You could also keep an eye out for special promotions or clearance sales at regular comic book stores.
The cost of manga in Japan varies. You might find bargain bins with cheaper options, but collector's editions or limited releases can be quite costly. Also, it depends on where you buy them - big chain stores vs small indie shops.