Your question is nearly equivalent to asking what cash value people assign to miles. There are various threads on this topic, but the short answer is: depends on how you use them. A common answer is 2-3 US cents.

Your itinerary is about 2888 miles roundtrip. In the worst case on AA (stopover in MIA, 3456 miles total), you would be paying $47 extra to buy 3456 miles, or $0.014 per mile. This is like getting a mileage run almost for free. Personally, if I needed those miles (and was planning to redeem them at an effective value greater than what they cost), I would do it, but I enjoy flying itself, so I wouldn't view the longer travel time as much of an inconvenience.