Using the price of 20 cents per log and 5 cents per plank, the price of other wood products is determined. I found these mistakes though:

Fence 15 cents
Stair 15 cents
Ladder 15 cents

To have these prices in line with the 20 cent logs, they should be lowered to:

Fence 8 cents
Stairs 7 cents
Ladder 5 cents

Here is a list of the items. The format is:

item name; item id; suggested price

oak fence; 85; 8 cents
spruce fence; 188; 8 cents
birch fence; 189; 8 cents
acacia fence; 191; 8 cents
dark oak fence; 192; 8 cents
jungle fence; 190; 8 cents
oak stairs; 53; 7 cents
spruce stairs; 134; 7 cents
birch stairs; 135; 7 cents
acacia stairs; 163; 7 cents
dark oak stairs; 164; 7 cents
jungle stairs; 136; 7 cents
ladder; 65; 5 cents

Here is how I came at these numbers:

it takes 5 planks to make fences (4 planks and 2 sticks... 2 sticks = 1 plank). That is 25 cents for 3 fences. 25/3 = 8.333. Round down to 8 cents each.

it takes 6 planks to make stairs. That is 30 cents for 4 stairs. 30/4 = 7.5. Round down to 7 cents each.

it takes 3.5 planks to make ladders (2 sticks = 1 plank). That is 17.5 cents for 3 ladders. Round down to 5 cents each.