When I started out in the production division I only had 4 mags for my XD40. That got me by just fine but 6 would be more ideal. I did have two times this year where I lost a mag out of my pouches, or dropped one on a reload!! I wished like crazy that I would have had one extra mag in my back pocket!
I will tell you what i am using for equipment. This stuff is all pretty entry level, but it is cheap and I didn't want to spend a lot of money before knowing exactly what I would want.
* Bianchi Duty belt with Velcro $30
* Bianchi inner velcro belt $23
* Fobus belt holster $18
* Two Uncle Mikes Double mag pouches $32
* SA XD40 with 4 mags $360
* 4 ProMag XD mags $44