Is my card worth grading?
In short: It depends on its condition, what it is worth raw and slabbed, and what the grading fee is. A pre-grade gives you an independent read of the condition so you can make that call before you pay.
The question is really a comparison: what the card is likely to be worth in a slab at its likely grade, against its raw value plus the grading fee, shipping and the wait.
I cannot make that decision for you, and I never promise a grade. What a pre-grade assessment gives you is the condition half of the comparison, read carefully and written down, plus which company's standard suits the card. Many cards turn out not to be worth submitting, and knowing that before you pay is the point.