The alternative are Philips Silver Visions. These don't give that blue effect but are silver/clear when unlit. You can buy both at
powerbulbs.co.uk. I have read to stay away from cheap ones from eBay or ones from halfrauds, Silvertec, I think. This is because they are dangerously dim when flashing.
I think this is the next mod I do to my Furby.