Spokes are cheap compared to labour, buy some and put them in yourself, buy The Bicycle Wheel (book) if you have some extra dosh.
Yes fatigue is likely the cause of your breakage; machine-built wheels are often not stress-relieved, and that may well be why.

I did see a run of spokes a while back that were breaking in the middle (unusual), a close look made me think they had been ground down to effect a butt, instead of being drawn
They were breaking at cracks initiated by any of thousands of tiny marks.
Run your fingernail along any new ones, drawn ones will be smooth.