Does anyone know of a place/store that would sell like a conversion kit for antennas?

I recently shaved my antenna off my car and wanted to see if there are other alternatives before getting XM/Sirius Sattelite radio.

For example, the Subaru STi's come with their radio antennas integrated in the rear windsheild above the defogger strips. The antenna looks identical to the defroster strips.

Does anyone know of a company that would sell/install something like this on my vehicle?

Any help is appreciated. I may just end up getting XM/Sirius sattelite radio.