For mags, I know CDNN has Mec-Gar and Taurus 15 rd. mags at same price; 17 or 18, 20 rd. (I think Mec-Gar) and maybe one size larger. They run from $20 on up. I recently bought 4 of the 15 rd. Mec-Gar and they worked well in the PT92.
I bought a OWB DeSantis 002BAV6ZO belt speed holster recently which is a perfect fit for the Taurus PT92/99 w/rail (as well as the Baretta 92 w/rail). It was also available with thumb break 001BAV6Z0 (replace B with T for tan color in both part numbers) - bought from OpticsPlanet and was in stock for immediate shipment - I have several DeSantis holsters - well made and durable, reasonably priced and usually freight paid by Optics. Fobus also makes some good holsters for the PT92 with or w/o rail. I preferred the leather. For IWB, bought one from AlienGear for the PT92 - took about 10-14 days to get it. Haven't bought grips as yet, but Taurus has a couple of nice ones on their web site, as does Ebay (quite a few) and GunBroker has many PT92 in plastic, wood and aluminum.
You can sometimes get good deals on them at Opticsplanet or ebay.
For Magazines, try CDNN, Greg Cote LLC, and Grabagun. If you still have to deal with a 10 round limit in magazines, get 10 round Mec-Gar Magazines.
Only buy Mec-Gar Magazines, otherwise your wasting your time and cash.
I use 10 round Mec-Gar Magazines for USPSA Production Class.