Great price and if the size works it might be worth it.  There are two differences between Ikea cutting boards and other mudflaps.

Most "designer" mudflaps are a thick polyurethane plastic that remains quite flexible and resilient to stand up to being pounded by rocks at really cold temperatures.  Polyurethane costs more to produce then other plastics.

That cutting board is made of a polyethylene plastic.  It is no where near as resilient as polyurethane especially at low temperatures. The most common thermoplast in use today. Its nice because we can easily melt and reuse it.  Who knows maybe that cutting board in a previous life was the seat bottom on a plastic chair.

Results:  Is a 120 dollar saving worth the reduced "performance?"

I say yes.

Thanks John.

Since they are so cheap, I think I will get my wife to get me 8 of them. That way if I damage a couple I will have spares. Apparently like Mark siad above they don't work well in the winter but I have regular Outback mudflaps for that.