Thanks for reading everyone!

So, I break a rear spoke typically about once a month. It's really getting frustrating and I'm looking for advice. I don't know much about wheel quality and maybe it's time for new wheels, but a few basics first.

Setup:
Globe Vienna 3 Disc
Rims: Alex rims 700c, alloy double wall, 32h
Rear Hub: Shimano FH-M475, forged alloy, disc 6-bolt, QR, 32h
Spokes: 1.8mm (15g) stainless
Rear Tire: Specialized Nimbus, 700x35c, 60TPI, w/ Flak Jacket protection
PSI: typically between 80-90

Payload:
6'0" Male
190-200lbs
Rear pannier/trunk bag
Approx. 10-15 lbs max
Total: 200-215 lbs.

Riding style:
Pavement, commuting.
Avg. 50 miles per week
Total mileage on bike is about 2k miles
Broken spoke count=8 (in the last 500 miles)


So, like i said, I keep breaking spokes (only on the rear) and it's getting irritating. I've replaced a few myself, but typically every 3rd one or so, I take it to a mechanic for a professional true. I just had that done at the local lbs about 2 weeks ago. I realize that I'm a little heavier than most riders, but not excessively. I'm in pretty good shape, so all my weight is not "in the saddle" or anything.

So where do I start?
Are the wheels I have decent? I thought they were, but I'm beginning to question that.
Do I need a higher quality spoke?


If you would suggest a better quality wheel, then I don't even know where to begin. Custom built? Off the shelf? Brands/types? Could I do only a new rear wheel, or is it most sensible to upgrade both? I dont are about wheel weight, just dependability. My budget would MAX at about $250. Is that even reasonable for a good wheel?

Also, if anyone wants to suggest a good starting point for "wheels for dummies", I'm all ears.

Thanks for your help everyone!

Cheers.