New liner for knackerd old pushchair?

[MrsBadger]

dragged the trusty old MX3 out of the garage now ds is about to outgrow the carrycot and tbh it's looking a bit... worn

thought of buying a new seat pad (the coloured bit in the pics) to smarten it up but the mx3 is out of production and nowhere's selling them any more

what would you suggest without paying £££ for a custom made and/or hideously frilled monstrosity

(I don;t need a cosytoes as the original one has washed up ok)