Jim, "sometimes" you can get an HVAC person who "moonlights" to do the charging of the system as part of the final installation. The physical installation is pretty darn easy. There is also a brand called "Mr Cool" I believe that comes pre-charged for customer install...but you only get one chance to do it right because once you open the valves, you're committed. Any issues or leaks, you need someone with the correct equipment and knowledge to take care of things. For mine, I worked a "deal" with the HVAC company I've used for years...the owners are friends at this point..and I did all the prep work and electrical so their installer only need to a couple of hours to do the final steps at a greatly reduced cost. They also gave me a very good price for the unit since I'm a regular customer.
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The most expensive tool is the one you buy "cheaply" and often...