I've never looked into scout scopes in much detail, but get the impression that good long eye relief scopes tend to be much more expensive than regular scopes.
For a "cheap" LER scope that works well on the M39, most of the guys on Parallax Bill's C&R forum seem to be going with the NCStar 4x32 pistol scope.
The only other inexpensive option they mention is BSA, but I'm not sure which BSA model comes with the right eye relief for the M39 rifle.
"Knowledge is power... For REAL!" - Jack Austin