Raise your rate if you're reusing a lot of code. You deserve to be compensated for it. Bottom line, the final price should be as much as they're willing to pay.

Raise your rate if you're reusing a lot of code. You deserve to be compensated for it. Bottom line, the final price should be as much as they're willing to pay. If you can't raise your rate enough (what do you mean $550/hour!), don't bill hourly.