Why don't you take it around to a few body shops and get some "estimates"and while you're there tell them you are thinking of doing the fender swap yourself and you want to know if they will quote just painting ... then see if they volunteer any advice on replacement difficulty.
But, if it is really easy it looks like you only save $50 or so if your selected body shop will charge Honda List Price. Plus labor which if it's easy, as it seems, might not be a lot. And with shipping again the dealer may be a better deal, since they get truck deliveries not single UPS packages.
Also you could just go ahead and start to remove trim, etc. (nothing to delegalize the roadworthiness of the car) to see if the fasteners are exposed. For example, the upper fastener at the top right corner of the picture looks like it could be hidden under some trim. And the headlight/cornering light assembly is involved somehow, not sure how.