Where I can buy this black foam?

Hello everybody, I want to ask your help mainly to informatics or electricians. My iMac crashed, and put an apple assistant, their response was that it was the power supply and how the model was discontinued not repaired, the result was this: I got home and turned on the machine and gave a short circuit and then smoke everywhere, open the machine and had disconnected cables and broken plastic, did not complain because I was going into the said and not said. Sent come a power source for eBay, only need to buy a foam to put together the power supply, which will have about 15 cm. does anyone know where I can buy this? iMac 24´ midd 2007. thank you so much.