Any auto parts store.
Usually called European fuse, bullet fuse, or VW fuse.
In any event they'll be hanging right there next to the blade fuses.
8 amp is the caliber you're after, and in a pinch you can take the fuse out of the VVT harness up by the oil vapor seperator.
It'll stop the VVT from functioning, but beats walking or a tow truck by a large margin.
(w/o VVT, the engine will start, run, idle, etc., it just won't kick the intake cam over into 'power mode')
Alfa made the switch from bullet type fuseboxes to blade fuse fuseboxes during the 1987 model year production run. However, even after the switch to blade style fuseboxes, the fuelpump and VVT fuses remained the bullet style.