It depends in large part on whether basements are expected--whether they're considered normal--in your area. In some places--as with places with high water tables or in really rocky areas--basements aren't expected. So a home without a basement isn't negatively affected. In other areas, though, where buyers expect a basement, it can affect the value.
It also obviously depends on whether the basement is finished (which can add value) or unfinished (in which case it may add relatively little value).
And it depends on the value of nearby homes. A basement in a home worth $600,000 probably will add more value than a basement in a home selling for $80,000.
Check with a Realtor in your area--and even specifically your neighborhood--for a more precise answer. Where I live (and this may not be at all reflective of your neighborhood, buyer expectations, etc.) a basement might add $10,000-$20,000 to a home's value, and maybe another $10,000 if it's nicely finished.
Hope that helps.