According to this: http://www.bacterio.cict.fr/a/azotobacter.html
the type strain is ATCC478
USD 255 if you are in the US. The strain is available from other repository (DSM in Germany, JCM is IIRC in Japan) and many companies can sell you a selection of ATCC strains depending of your country. Shipping from ATCC to a different country is possible but can be tedious as you need to be certified by your country and have the papers to show you are before the ATCC ships anything.
on the ATCC.org you will find the recipe for the recommended media for propagation. Some interesting ingredients in it.
Pubmed might help you to find a procedure for isolation. I don’t have a clue.
Microbiology with weird species might be an expensive hobby though, with the price of selective media…
