The best method for estimating the market value of any property in question is to simply place it on the market and observe the amounts being offered. The main issue with this method is that nearly all Sellers are disposed to overestimate the value of the Apartment/Unit. The Sellers then allow high prices to persist without if required/necessitated rapid proper price reductions. This ultimately may result in a lower sale price than what could have been gained if the Apartment/Unit was priced correctly from the onset. In order to obtain the market value of an Apartment/Unit, you can simply search a recent sale of an apartment in the Building. After gaining this information you would need to adjust for variables such as condition, views and floors. Excellent resources for making an appraisal may include:
However, the best method is to discuss the issue of pricing with a real estate broker and/or your real estate attorney.