Some information on the key features would be helpful. Oboes typically are divided into three categories depending on the key work;- student, intermediate, and modern/professional. Some photos would help with that.
I would say look in the oboes "sold" listings on ebay for the most similar instrument to the one you have if you can't find one that is an exact match. See what the range of sold oboe prices is. Consider the condition of the other parts and case as well.