Edit- On a 2006 for sale, I would re-fasten the piece you have there. The damage is minor and can be straightned and re-fastened.
If you want to replace the whole strip...
Well, on a scale of 1 to 10 on the RV handy person meter.... I would put this at about a 6. The corner bead is a common piece and can be purchased on Ebay. You will also need some Butyl tape and Dicor non-sag sealant.
On the other hand... at the dealer, should be less than a few hundred bucks to have it done by them.
I would fix what you have and seal it real good with products above.
Keep us posted.
2017 Salem Villa Estate 395RET-
2011 Coachmen Freedom Express 295RLDS- Sold
2015 F-250 FX4