Good luck on your search, I had some years and years ago in the "pop" cans. I slowly depleted my stash and converted to R134. I looked in my garage to be sure and have nothing remaining. I did find my gauges though, even the can tapper LOL
Expect to pay about $80lb for R-22. A 2.5 ton unit may need up to 4lbs. That price may or may not include labor to install. Sorry I don't have someone to recommend.
When I mentioned your unit was 12 years old, he thought I was asking him about R-12.Not me, Hubby.You found some?