All well and good to say "take your money and put it in a jar (or wherever else) and pay for the repairs when needed" but I am sure many folk take it back out of the jar or don't put it aside religiously, especially when that cool new costly asscessory appears to be indispensable.
This approach is all well and good if (a) the money can be accumulated fast enough to cover one or two simultaneous expenses and (b) if you are not only able/handy but have and acceptable physical location to enable you to work on the trailer. These are considerations that might be missed when making this decision.
Extended warranties are good for many folk, aside from the undeniable "peace of mind" especially when the cost is balanced with the benefit. As with any type of "insurance" you may never need it but if you have it when you do, you are usually glad you did.
I have the extra year of FR warranty for $150 and also have a good extended warranty on my truck, bought when the truck was bought new. Works for me.