polymorphself , if the bike only has 50 miles on it then it's safe to say that the spokes have never been stressed. Given that, I'm going to make a suggestion.
Re-use the spokes.
1) spokes are not cheap as you have discovered
2) there is nothing wrong with the spokes you have other than some mild surface corrsion
3) this is your first build so you have some learning to do
4) there are degrees of wheel build quality, your first build may not be perfect so no need to waste a good set of new spokes
5) if you haven't already done so, buy a
spoke length tool.... wheel truing stand.... and ....dishing tool
The easiest way to clean spokes is to soak them in something like this and wipe with a
green scotch pad....Test on one spoke first.
