If you mean "new" as in a crate engine through the dealer, that will be very expensive. New engines typically only are supplied for warranty replacements and project cars.
A used engine from a salvage yard is much more common but you don't know its history or whether it was abused before someone hauled it to the yard. An engine from a crash victim will be more likely to have been well cared for.
I prefer to rebuild my engines because you're starting with a known quantity. You get to decide the quality of parts used. Also, it may be possible to perform a simple repair vs. An entire rebuild. You have to look at the miles too to get an idea of how much life is left in it. If it's over 200,000 miles, a total rebuild might be a better investment.