My upper fairing stay is broken
No surprise there. The upper fairing stay is one of the first things that can get bent on the EX250, and they are hard to find used for a decent price in "untweaked" form. We recommend trying to fix the one you have, if you have any welding skills (or a welder-wielding friend), especially since it costs $135 new. And when you fix it, make it beefier.
Part # 11046-1289; third owner, 16,000 miles
Repairing the one you have
If you still have all the pieces, you can just get someone to weld them back on. Weld the broken pieces together, then run a weld along the bracket to strengthen it. This one has gone 15,000 miles since the repair. It's stronger than the original and still works fine.
Making a stronger bracket
The bottom part of the bracket (stay) was designed for obsolescence. Bring the pieces to anyone that has a welder and have a new piece welded to the bottom of the strut. Either 3/4" or 1" flat steel strap can be bent, drilled, and then welded into place. The strap will have a lot more strength than the lightweight piece that Kawasaki uses. It will weigh a few grams more, but it won't break again.
Here are the measurements that one of our guys came up with. YMMV. He used 3/4" wide x 1/8" thick flat steel, with these approximate dimensions:
You can also mount the new part without a welder -- use a long bolt through the strut to hold the new bracket into place. You may need to trim the bottom of the strut if you use the bolt; there isn't a lot of clearance where the bolt head goes.
To remove the broken bracket pieces, grind down the weld on the end of the fairing stay, then beat the bracket ring (all that should remain after the angles snap off) right off the end of the fairing stay post. Here's a couple shots of the fairing stay with the old bracket remains removed:
Measure everything and have a bracket made from some steel scrap. The hole in the center of this picture allows the new bracket to slide over the fairing stay post seen in the previous pictures as bare material:
With the upper fairing stay bracket removed and the tube cleaned up, position the new bracket on the tube. Weld it on. The end of the tube should not protrude through the hole in the bracket, since there is minimal clearance to the frame in that area.
The thicker bracket material will require new hardware to mount the stay to the frame. Something in the neighborhood of M6x14mm bolts is what you should need.
It's important to note that the lower corners of the bracket need to be removed to clear the steering stop on the lower triple tree as the handlebars are turned. Use a Dremel tool cutoff wheel and clean up the edges with a grinding stone bit.
Pictures showing the new bracket holding the fairing stay in position: