I can’t stick one of those in my pants because I get funny looks ;)
I do have a metric ton of Glock mags, back from when you could get them from police supply warehouses for about $13 a mag. The went up to $35 for a while, but they apear to be down around $22 to $25, which is manageable.
With my little Sub2000 in Glock 17 configuration, I use the 33 rounders at the range. But I prefer the factory 17 round mags for carrying the weapon in a vehicle. Silly little carbine came with a ten round mag! Of course five 17 round mags is the minimum for amusement purposes.