Sports shoes are generally more expensive than shoes for casual walking. Less than a $100 can get a good pair for walking. However, if you are retiring your running shoes you can use them for walking
Those casual shoes aren't always ergonomically designed... I would only trust proper running or walking shoes... in the end, the shoe must fit your feet and must be stable when you stand or move... it depends entirely on how your body is made and how your feet are like... some people can wear cheap shoes (like my dad) and don't suffer any issues even with long distance walking... but for me, once no arch support, the pain can be unbearable... even at home my slippers have to have arch support... so buying shoes become very 麻烦 cos must try out many pairs, take out the insole put in my custom insole and then lace properly and walk around for about 5 min or so...
Also most running shoe brands are angmo brands, so their feet are longer and narrower in general, so these shoes cannot fit my wider than average feet... I've tried almost all brands in the market - Asics, Nike, Adidas, Reebok, New Balance, Puma, Brooks, Saucony, Hoka, On, Under Armour, Skechers, Decathlon (Kiprun), etc.... for me, Adidas fits the best... once you put on the shoes, you know if it fits... Nike & Asics too narrow, Hoka's footbed just doesn't fit my sole, Skechers are too unstable, Reebok & Saucony's toebox are too low, Puma & New Balance also got fit issues (even with half sizes), while On & Under Armour uppers press to hard on my instep... and not all Adidas models fit me also... only those with curved lasts will fit, those with straight lasts do not... plus if the heel drop is too much also got forefoot pain...
I also used to think like you, use my running shoes for walking after they're worn... but I realized they have been worn in in such a way that they don't fit my feet for walking... so cannot reuse... so nowadays I just run until the shoes cannot then I just give away (if still good) or throw away... anyway I don't run that much... one pair can last about 1.5 years...
Those skate shoes, platform shoes, plimsoll-type like Onitsuka Tiger, Adidas Gazelle, etc... with completely flat insoles, these are the worst shoes to wear... your toes have nothing to grip, your arch has absolutely no support, and wide mouth/opening means your ankles have no support cos the shoes are not being strapped properly to your foot... just for show... don't torture your feet please...
Just my 2 cents after many years of suffering feet pain, especially on holidays...