I would like to find out if a Van Gogh I bought has any value?

I am aware of all the Van Gogh sunflowers replicas out there but I bought this oil painting at an estate sale it's signed Vincent on the front and the back is stamped in red ink VT385 Van Gogh: Sunflowers 18x24 it appears to be older the frame and paper on the back showes age. Does anyone know how to find out if this has any value?