Rather than replace my lawnmower blade I sharpened it for basically nothing using an angle grinder and a sanding flap disc I already had. 5 minutes later it's cutting like new. :
What should a sharpened mower blade look like? - Quora
How to Sharpen Lawn Mower Blades (DIY) | Family Handyman
Do Brand New Lawn Mower Blades Need to be Sharpened? - Lawn Chick