Assuming you are figuring a construction budget, (including materials and installation), very roughly, and subject to plant material spacing and species, you could use $3.00 a sq.ft. for groundcover/shrub bed areas and come out fine for such a project. You should break out your trees (depending on size $200-$300) and irrigation ($.33 s.f) separately. These are decent numbers for the southeast.
Disclaimer: geographic location influences costs.
