There is a fisher cube on Amazon for $6.99 but it has stickers. There is a lot of packs on Amazon that include the fisher cube, so I would look around at those.
On the yellow side, the corners are the triangle pieces, the center is the diamond/square, the edges are the house-shaped pieces. On the orange side, the smaller rectangles on the right and left middle layer are the centers, the rectangles in the corners are edges, and the middle piece is an edge. They are weird just like the windmill cube, but you'll get used to them.
You solve the fisher cube like a 3 by 3. Using your knoledge of what the pieces are on the fisher cube compared to on a 3 by 3. Like solving the white cross with a center and 4 edge pieces.
For a video on how to solve it: https://www.youtube.com/watch?v=J05d_9imm3k
This parity on the fisher cube is solved the same as on the twist cube. The parity is when you have an odd number of correct edges when solving the yellow cross. To fix it, hold one of the yellow edges at you, (like shown), then do this algorithm: R U R' F R' F' R U2 R U R' F R' F' R
This parity on the fisher cube is solved the same as on the twist cube. The parity is when you have an odd number of correct edges when solving the yellow cross. To fix it, hold one of the yellow edges at you, (like shown), then do this algorithm: R U R' F R' F' R U2 R U R' F R' F' R