undercoating

Ok, so for all the people, or persons living in places that salt during winter, did you opt in for the undercoating from dealer or did you save money??
Myself, I opt'd out. They charge $2000 for the undercoat which gets added to your loan, x % interest, over say 7 yr term loan, that's alot of money. I did get the 3M protection though.

But, and I've done this on every vehicle I owned, I bought the spray can stuff and done it myself. Thinking about doing the same to the blazer, but unsure what good and whats not out there for the spray can undercoating. Or is asphalt or non-asphalt is better/ useless.

Lets see some opinions and suggestions.