OEM Glock mags are expensive because Nioa are the local importer/distributor.
Magpul mags are fine. Fellow club members have used them for ages with no issues.In the US you can get Magpul mags for ~$US12 whereas Glock OEMs are ~$US25 normally. If you're buying from Brownell's Australia just note they will take at least three weeks and probably longer to arrive depending on how much stuff they are getting shipped out here at once.
You can buy from Brownells US site and if you keep it under $US100 (this is supposed to change this year following ITAR amendments) you don't need an export permit on the US end. All you need is a B709 on this end which is free from Firearms Registry. You can get 7x10rnders for under $US100 but once you add postage its probably about the same cost as ordering through the AU website. I'd expect the AU sites prices to rise fairly soon as well now that the AUD s so weak.
https://www.brownells.com/magazines/han ... r_1=magpulAs for your Beretta mags, MecGar make mags for them and they should be cheaper than Beretta OEM mags. MecGar have been in the magazine business for decades and have made OEM mags for other Beretta pistols in the past. They also make almost all of Sigs OEM mags. I would never hesitate to use a ecGar mag, they make great products. If you ring Gold Coast Shooters Supplies they normally have them for $70 and can mail them to you. Their website is terrible as it is a small shop run by an older guy ut they have heaps of different mags.