Looking at trying to improve the reliability of my 22 build and I was wondering is this kit really worth $189??

double tap

I run a stainless CMMG B collar conversion on a CMMG 9" barrel on my SBR for Steel Challenge... I run a Bore Buddy firing pin (after an OEM pin broke) and their wire EDM extractor.... other than that the rest is OEM CMMG... I have machined a step in the rim of the buffer so that it protrudes slightly into the upper to provide some pressure against the end plate... I use steel feed lip Black Dog X magazines that load to 23 rounds... using CCI Blazer or SV that measure .222" I get exceptional reliability, with one failure to fire in 3 years of competition and practice at about 1200 rounds a month.... I have broken a RRA NM hammer, and currently use a LaRue MBT trigger group as I like the flat face of the trigger... the addition of the BB firing pin and extractor IMHO was an excellent addition

the strike end of the BB firing pin is circular and not a wedge, and strikes the cartridge just below the rim where it does not have to dent the strongest point of the rim...

I am using the Bore Buddy firing pins and bolt weights in my AR22's. Bore Buddy's firing pin is a better design than the CMMG firing pin. The bolt weight helps with bolt bounce and as an added benefit, it keeps the inside of the receiver cleaner too.

I am using a BB pressure plug in one of my AR22 rifles, the other has a TACCOM pressure plug. I am just running and end cap on my 4.5" pistol with puts enough pressure on the bolt to keep it from moving.

What kind of reliability issues are you having?  I'd say most cycling issues are resolved with good magazines.  Black Dog magazines to start.  S&W 15-22 mags with a spacer or a redi-mag adapter.  Those are all great additions to your AR22 but I'd start with the magazines, pressure plug, then do the firing pin and extractor.

There are 3D print files out there for the Buffer plug and Bolt buffer. I printed the plug out of PLA, for the bolt buffer I used TPU95 and doubled the thickness. I did see some improvement in reliability with them.