I may have misspoken when posing the question...

My belief is:

If a man is ordered to take a DNA/paternity test and he is determined to be the biological father, then I agree with you that he should incur that expense of testing.

If a man is ordered to take a DNA/paternity test and he is determined NOT to be the biological father, then I view the woman who implicated him as being culpable to reimburse him for the expense of testing.