If the water is as shallow as it seems in the picture, you can easily go to a pond store and pick up some flat sandstone or slate real cheap and make the ramp and basking area. The turts will not be able to move the rock and you'll have a natural basking spot for them. You could make the whole thing with 3-4 small pieces depending on your construction. A local koi pond place near me charges like 12 cents a pound (not sure what that would be in Canadian money).
If you choose to fill the tank higher, you could make an above the tank basking area out of a sheet of acrylic using Joey's method for bending acrylic (torch) but I'm not sure if that's as affordable for you.