I tackled this earlier this spring. Built the hearth out of 2x4 wrapped with a 3/4 inch ply. That was covered in 1/2 in cement board and topped with wood look ceramic tile. Backspalsh was stacked slate and the stove is a Heat n' Glo natural gas unit in dark cooper/ bronze.
Materials: $600 +/-
Time: 3 Weekends and 396 cuss words.
Stove: $3,400 minus 10% veteran discount
Stove Install and Mechanical Permits: $1,540 (which included 3 way gas lines to power more stuff later)
$6,240 +/- all in for this DIY project.
Project gave me an excuse to buy a tile saw and a few more tools.
I'm currently Jeepless so I needed a project to keep me occupied.