$16.00 may seem a little high for a spring so let’s rationalize it in several ways…
1) the M and M-A1 aren’t even in current distribution in the US. which means…
2) Steyr isn’t producing or exporting recoil assemblies from Austria in any great quantity.
3) BT removes the spring from the factory plastic rod, meaning that part of the $16.00 went to covering the cost of the rod and the cost of putting the spring on the rod.
4) If you decide to experiment with an alternate spring, you’ll likely pay $8 + $5-$10 in shipping just getting the spring to your door anyway.
THEN, you get to figure out how many coils to clip to make it both travel fully rearward AND solidly lock the slide into battery.
THEN you’ll likely spend $20 on ammo so you can drive to the range and test to see if it works. If it doesn’t?… back to square one.
Knowing this, $16.00 starts to look like a deal for a drop-in reliable part.
Some people just have to tinker with their pistols to get them the way they like them. If you’re one of those who likes the thought of taking on a little project in the pursuit of personalized Steyr perfection, B~T offers guide rods that use Glock sized springs for your Steyr M/M-A1 Series. A close match would be an 18 pound G19 spring