You haven't looked hard enough at SVP. They have genuine Verbatim, unbranded Taiyo Yuden, TDK, and Plextor media, all good and reliable media (with the expection of 16X -R TDK IMO).
Now your problem is that you need true multispeed media for your 1X-4X recorder. What I've used for long with excellent results @1X in my own standalone recorder are the Verbatim 8X -R (MCC 02RG20), but these are extremely difficult to find now.
The 16X -R Verbs (MCC 03RG20) are very speed-tolerant too, you can give these a try. A friend of mine has good results in his E55 with the TDK-branded 8X -R TTG02, but I see these aren't available anymore at SVP either.
Another possibility is to check at Panasonic if there is a firmware upgrade for you recorder, which would probably allow the use of most 16X media with acceptable results. Who knows.
If all fails, use this trick if you have a good PC burner: record to RW on your E55, then rip and burn on your PC.