Because you identify yourself as a Home Buyer it sounds like you found something you like but are not in agreement with the seller about the appropriate price. Usually the buyer is in the driver seat. If you have a
real estate professional representing you it is her job to negotiate a reasonable compromise that is a win win
for both buyer and seller. Not an easy task if she has no comps to use that are appropriate for this property.
An appraiser would break the property down and give value for each component but would need three comparable sales for a valid appraisal. You may wish to pay for an appraisal to arrive at a "true value".
If you ask the question because you have been denied a loan because the property didn't qualify, you can offer to pay for a second appraisal. Your realtor will meet the appraiser with a prepared list of the extras that "set the property apart" with an estimate of the value of each extra.
Good luck! and contact me if you would like more advice.
Coldwell Banker Property Shoppe