Welcome Claude1, you can try this for an online collector price guide: http://numismedia.com/rarecoinprices/fmv.shtml All price guides have limits, but it's good enough to give you a sense of if your coin is worth melt or 100x melt.
My question is why are you considering having a coin professionally graded before you even know what you have? The grading services are there to pinpoint the condition and determine authenticity so you can always know what your coin is, and is truly worth. You should never just send in random coins unless you have a good idea of what it is, or if you are taking a calculated risk of some sort.