simple things, simple pricing:

(size material $ price)

5"x 5", oil on panel, 125.

5"x 5", oil on canvas, 135.

6"x 6", oil on panel, 145.

6"x 6", oil on canvas, 155.

6"x 6", oil on linen,    165.

6"x 9", oil on canvas, 175.

8"x 8", oil on panel,   185.