As for the .22 idea ... my local club's land owner just recently banned "loud" guns from two of the three ranges we use. So, some monthes they have pistol/shotgun stages on them, but other months they've had pistol caliber and .22 conversions run. Had some running suppressors on their rigs too! AWESOME!
I have a moderate $$$ tied into my gear. I used to place well, but lately have slipped .. but that's mostly due to a lack of practice on my part.
As there are no widely accepted rules, some gear may do better in some circles than others. But here's what I'd recommend for decent setup:
A 40 cal doublestack. Hard to beat a G22 here for price. Could add a magwell and extensions to your mags and likely remain "legal" in most matches ... might pick up a 30 round mag for the times they are allowed. This will hit steel a little harder and keep you out of minor scoring that some matches would put you in.
Base gun $500 (or less)
You'll need holster and mag holders and then you can add whatever else floats your boat.
Rem 1100/1187. Shoots softer than a pump.
~700 but you can find these very cheap used at times.
You really need to extend the mag tube, and you'll need to add ways to hold shells ... often on gun, but many prefer belt mounted caddies.
Lastly rifle.
I'd suggest grabbing an AR with a flat top, armalites 1 piece scope mount and a simmons prodiamond turkey scope for an inexpensive way to play. Free float the bbl ... and drop a JP trigger in if you can afford it!
Base rifle ~800 (but you can spend MUCH less if you try ...).
Scope and mount = 200 (or less, those scopes were clearance at CDNN sometime back for $50!).
Better add 75 for some decent mags and belt holders.
Say $700 on pistol, $800 on shotgun and $1075 for rifle.
That sounds like a ton (heck, it is a ton) but I was salivating over a nice $2600 competition AR just yesterday.
but if you buy used and catch good bargains I think total outlay to play could shrink from 2600 down to 1800.
But shooting whatever pistol you own, a pump shotgun and an iron sighted AR could get you much lower ... and still is quite a bit of fun!