Tom, First of all I do not know what a alta survey is.
If you are buying vacant land and do not know where the boundry lines are you might want to do a pin and stake survey, they are quite expensive most are more the $3000 and could cost as much as $6000 just depending on the size of the land and where it is located and how many creeks, underbrush and valleys they would need to go over.
If you are speaking of property in the city, most often a mortgage plat will work and give the boundry lines, unless there is a dispute with the neighbors as to what is build on the property lines. Most pin and stake inside city limits will cost under $2500 whereas the mortgage plat is $200 paid by the seller at closing.
Buyers will usually pay for a pin and stake and not the seller, unless it is written into the contract.