Just guts, save the enclosure? Only 13 circuits, assuming no outstanding compliance issues, it seems like a half day for efficient direct labor, unless I'm missing something. I've done full new 40-odd circuit panels in as much time, but demo will take a bit, and I don't want to rush...
Add in inspection time, quote time, drive time, might as well round up to a day. Everyone has a different labor number there, and different markup.
Overall, $5k with your materials price is fair to me, but I'm low usually, so trust the other guys' numbers perhaps more (I'm assuming peters' $2k incl markup so we're both in line if that's the case).
(also a new EC, so my numbers are posted more for feedback than reference)