Ahh so it's more of a "steampunk" project than a digital weather station.
Cheap panel meters from
Marlin P Jones Sales. His stock varies, but all he has right now are square ones. Call and he may have some others in smaller quantities.
All Electronics has some interesting edge meters.
Surplus Electronicsand the
Surpls Sales of NE have been places to find other shapes and sizes.
Other resource would be a hamfest, you'll find a variety of meters in different sizes and shapes.
ARRL Hamfest locator will help with ham's in your area.
I like the servo idea to move the indicator around. That way you could nest the pointers and make it exactly what you want the final product to look like.
Added bonus is the sound of the servo's moving things around as it works.