I don't think you can find online. Realtors may have some info, but on lots it is often imperfect. Of course it will depend on size, access, location, suitabless for build, activity in the area, etc. Lots and lots of factors. Probably the best thing to do is have your realtor pull a list of active and sold lots in the area and then start testing the market together with a price you both can agree upon.
Contact my office if I can offer further assistance.