I don't know exactly which turnout you have, but as everyone else is saying you don't need to protect each individual turnout with a fuse. One, and only one, AIU turnout is "active" at any instant. That is, an AIU fires one of its SW relay outputs at a time for exactly 0.5 seconds. And hence 1 fuse can protect multiple turnouts.
You can get resettable fuses for about 15 cents a piece (free ship from Asia) on eBay. The cost is not the issue. It's the hassle of installing or wiring up many fuses when only 1 is needed.
The Amp rating of the fuse depends on which turnout you have. As to whether you even need a fuse at all for AIU SW outputs is a separate discussion...but if 15 cents is make-or-break, you ought to find a different hobby. 
