why is part #48610561A so expensive??

[desmodoktor]

hello , just wanted to know whats the purpose of part # 48610561A on my 02 m750.
the original one, over time went bad and the foam turned to dust .. one day when i lifted the tank it broke and i threw it away without knowing what its purpose being there was.
today i thought of ordering one , but when i went to look for it the price was 174$ !!!   
i dont get it .. its a piece of cloth with foam inserts.... why so much?? what does it do really? keeps the heat down from going to the gas tank .. ok .. i can make a similar one from exhaust wrap, just cut it and stick it there or smth .. 

[Raux]

Noise reduction

[Howie]

You don't need it.