Below are the standard course and dive prices, but naturally they are subject to change. While Utila [1] used to be significantly less expensive than Roatán [2], that’s no longer such a big factor, especially for dive courses.
When budgeting, remember that courses on Utila include hostel-style accommodations if desired, and that the required accompanying dive book can run US$30 and up, depending on the course. Prices outside of West End in Roatán [3] can be a bit higher.
The Open Water certificate at Coral Bay Resort on Guanaja [4] costs US$375.
Links:
[1] http://www.moon.com/destinations/honduras/the-bay-islands/utila
[2] http://www.moon.com/destinations/honduras/the-bay-islands/roatan
[3] http://www.moon.com/destinations/honduras/the-bay-islands/roatan/west-end
[4] http://www.moon.com/destinations/honduras/the-bay-islands/guanaja/accommodations/dive-resorts