Shoulder holsters on a budget :
This one seems to fit semi-auto’s a little better:
Amazon
This one seems to fit revolvers ok also (judging from the photo):
Tacticon (has a coupon code on their website for 10% off)
They each have retention straps with elasticity which easily already self velcro’s to your belt (so less flopping around), and broad padding on the shoulders as opposed to most leather ones, Alien Gear excluded.
You might want to read up on size/fit though.