Herbert Chapman's Bust

Hello, I need to pick your collective brains please. As the topic title indicates, its to do with both of them. One has started to leak and the other is not far off. To get a new pair from Yamaha - £250 + VAT. I've not got that kind if money so where can I get comparable bits from? I've looked on EBay and the likes of Yambits, etc but no success. So can you help? The bike is my transport to work. Without it, I'm buggered. Thanks in advance HCB