Time for new running shoes?

Hey everyone, so I remember last time I was a runner (3 or so years back) investing in a pair of Gel Kayano 24 and it was like running on marshmallows, wonderful, I have extremely flat feet and these are the perfect fit for me. Now at the time I had the money(129) for them, but now I’m on disability until dec and can afford a maximum of like 80 quid x I’m running. On Adidas cloud foam atm (present) but I’m wondering how many miles until you’re supposed to buy new? I have a dodgy set of knees(am 13 stone and 5,9) and I have ankle grinding feeling sometimes? I’m thinking how long do I have to save up the 129 again for my fave pair??any help appreciated!

[2718281 Graduate]

Try searching online, if you know that the kayano 24 are good for you, being the model from 2 years ago, you will be able to find some offers