shipping discounts or coupons for physical for non subs

i would like to buy multiple physical books from the site, but the issue would be tax and shipping, sure i should just buy subscription and not complain about this. also i notice other sites will offer coupons via how much you spend,being able get free shipping or reduced if you spend lot of items. reason i suggest this because it will help competition and will make customers who are willing to buy physical versions of media like myself some aren't interested in the comic mags or anime just the books and doujinshi.