It also is possible to do your own cost comparison through researching comparable properties recorded at local county recorder's and assessor's offices, or through Internet sites specializing in property records. See Comparative Market Analysis
(Beware: internet or "online evaluations" as they're called, can be as much as 20% off both high and low because there is is no one there adding or subtracting value for missing amenities, property condition, and improvements. This is the type of subjective analysis that only a REALTOR can do.)
However, there are other important contingencies your agent should consider adding to the contract as addendums:
In recent months, due to changes in appraisal regulations as well as the number of foreclosed sales used as comparables, banks selling REO properties are refusing offers with appraisal contingencies. Why? Because savvy buyers have been offering high prices, knowing full well that the property won't appraise for market value, and the price will have to be renegotiated to the appraisal. This situation is probably only temporary, however, as appraisals will eventually catch up to the market.
The purchase contract should also outline important seller responsibilities that although part of the standard contract could also be categorized as contingencies. Such things as :