Little Mermaid cost around $100 mil, correct? That includes projections, multiple large full-functioning AA's (Ariel 1, Ursula, Triton, Ariel 4, Eric 2), smaller/less detailed movement AA's (Scuttle 1 & 2, Ariel 2 & 3, Sebastian, Flotsam & Jetsam) , restructuring the entire building, audio, etc.
Mater has a turn-table based ride system, non-moving scenery, and ride vehicles, with a POSSIBLE large semi-moving Mater (though I doubt he'll really move, it will probably just be audio).
There's just no way that they both cost $100 mil.