Your picture is not close up enough to see the individual fabrics for me, but I think you could get a good idea of the age of the fabrics from members of a quilt guild (those who have an interest and experience in vintage fabrics, as well as having the published books for research). The cost of an actual appraisal might use up too much of your potential profit.
Before you start quilting it, examine it closely for open seams, stains, etc., as well as quality of fabric (sturdy, colorfast?) Also look closely at how flat the whole top is. If it won't lay flat, it will present challenges for a machine quilter, but might be able to be eased in during hand quilting or tying. People did tie quilts of this type sometimes, so that might be a quicker cheaper option to turn a profit.
Vintage tops less than 100 years old are not rare. Condition and style has a lot to do with resale value. We learned recently at a presentation by a quilt appraiser at a local event that common quilt patterns do not command a premium.
The potential buyers need to be people who are interested in the charm of a vintage quilt.