Where are you located? I can only speak on how it’s done here, so if you’re in the US, if I were in your position, and there are no solid comparables to use, I would go ahead and pay for an appraisal to be done. A buyer who is obtaining financing will be required to have an appraisal done by there mortgage lender anyway, so if you go ahead and pay to have one done before listing , at least you know you are pricing your home right and will know what to expect. You can also use your appraisal as a negotiating tool in case of low ball offers.