Overshoes? Yeah, maybe, sometimes more. Generally my £20 winter gloves will last 5 years or so, I expect most of my cycling kit to last a few years with the exception of consumables like tyres, chains etc. If I can double or probably treble the life of something like overshoes, then why not? Don't get me wrong, I'm not some kind of ultra thrifty commuter
But I don't think it's unreasonable to expect more than a few months out of a piece of cycle clothing, even if it 'only' costs £20.
No need to apply duct tape to your overshoes