I got 2 File:a50qs.pdf fuses from Alan's Sales. The plan is to use one of them in the car, and keep the other as a spare so I'm not ever tempted to drive without a fuse. Hopefully it will never blow. Shipping to New Zealand was only US$12.70, unfortunately I wasn't able to use Buy USA because paypal want the addresses to line up.
- LittelFuse 477p series has 400V dc rating but is slow blow. http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=F2985-ND
- Bussman FWH-.500A6F looks good http://nz.farnell.com/bussmann/fwh-001a6f/fuse-1a-semiconductor-hi-speed/dp/1701383
- LittelFuse 216 series looks worth testing, same 5x20mm ceramic body as 477 but only 250V AC rating.