I set up my second oxygenation system with just the O2 stone (on the stainless wand) from
Williams ($34.90), a flow meter O2 regulator ($20-$40 on ebay or Amazon), a few feet of 3/16" beer line, and a brass swivel nut to connect the tubing to the regulator (maybe $1 from a welding supply store). I picked up two 20 cubic foot O2 tanks from the welding supply place, full of O2, for $100. Of course, I traded in my 5 years out of date (hydro stamp was done in 1997, only good for 10 years) at the time, to get the better rate. Still, even if you paid ~$100 for the full 20 cubic foot tank, that's going to end up costing you less than using the 1.4oz tanks you get from hardware stores. Especially when you get the precision from the flow meter O2 regulator.
I use 1Lpm for my 'normal' OG brews (under 1.075) for 60-90 seconds. With the pure O2 setup, you have zero need for the filter. You DO need the filter if you use a pump.
I make it a point to NOT touch the stone with my bare hands, ever. The original wand I picked up is still using the plastic bag it came in, so that it's protected. I'm using aluminum foil to cover/protect the new one. Williams has updated the wand instructions to include a StarSan soak to sanitize it. It used to just list boiling, but no longer (lists both methods).
If you want to start off spending less, in the short term, then use the cheap O2 bottles. At some point you'll probably get frustrated with not knowing how much O2 you're really sending into the wort, as well as burning through the tanks faster than you had expected. Luckily, it doesn't take much to adapt to a 20 cubic foot O2 tank for the wand.