Polar IR Compatability

Matty1235

I have recently purchased the CS400 at a bargain price (otherwise i'd have never bought it). But i now find out that i need to purchase the cadence kit at £22 ok fair enough, then the Infa red at £40. Does anyone know if you can buy a simular non branded device to do the same job or am i stuck shelling out £60 on these two extras?

Thanks in advance!