I need to replace the a/c condenser fan for my 2004 suzuki xl7 since it is not working. I checked and the original fan cost
approximately $350.00. Does anyone know if there is a replacement fan/part (not original) that will work with
the a/c units for this suv.

I was told that since this suv has double a/c units (one in the front and one in the back), you require to purchase a fan that will work with both a/c units and for this reason it cost so expensive.

Universal a/c condenser fans cost about 60-100 dollars however
they are for single unit fans and i am told it will not work properly with my suv.

Please advise, thank you.

Universal fan will work fine.  The fan on my 4-cyl Tracker and the dual-air XL-7 were nearly identical.
 
I'm not getting the feeling that whomever is giving you the advice really has a grasp on how your dual air works.  Your truck still just has the one compressor and one condensor.