New install

I am currently installing my sprinkler system. The most outer zone is at the end of a 200' main line. I would like to be able to blow this out myself at years end. My question is there a blow out valve or something I can install at this zone so I can attach my air compressor there to blow that zone out?

I don't think there is an automatic valve that would open to air pressure but not to water pressure. All you need to do is put a regular ball valve on the end of the line. You didn't say what size the line is, but that's a pretty long piece of pipe to blow with a home size compressor. I have 4 zones that I blow with my 60 gallon tank, but I use two tank fills to do it, The pipes range from 1-1/2" to 3/4" and maximum length is about 150 feet.

Guess I didn't read you question quite right. You can make a valve that will work using adapters and reducers. You will need to figure out how to connect to the water line, but that's just a matter of a valve and some fittings.

Extend the irrigation line past the last head. At that point install a valve box to accomodate a garden hose connection attached to the irrigation line. Using adapters, connect your air compressor at that point. Keep your air pressure at around 50-60 PSI for 4-6 minutes. This is only an idea. I would be mildly concerned about having pressure introduce into the line on the opposite side of the underground control valve.