Dry base rock is really cheap. I got BRS pukani rock which seems expensive, but the rock is so porous that you don't need that much. I'd say 1/2-1lb per gallon would work..maybe even less if you want. I bought 100 lbs for my 70 gallon and only used 3/4. There are 12 one foot rocks and 3 huge two feet rocks. They are fairly easy to aquascape b/c they have a seamless look (fit together nicely) and there's obviously no pests if that's a concern.
I know I sound like a salesperson, but I just really love this rock and wanted to recommend it to you
BRS Pukani Dry Aquarium Live Rock - Bulk Dry Live Rock - Bulk Reef Supply