When I bought my B20, I had a Peavey MAX 110 right beside it for comparison. Both were solid but the B20 was clearer with a great tone. The Peavey had a modern/vintage voicing switch but it did next-to-nothing. The Peavey cost a bit more too.
Now, the previous poster's point was that they are good quality and someone could pick up a used one for less and that is a valid point.
Frankly, however, ~$100 for an decent practice amp is low enough for most of us to just buy new; leaving the option to return or exchange a defective model and having the warranty.
BTW - I generally don't buy any extended warranties but I certainly wouldn't buy one on a $100-$120 amp for $35. That's a 25%-30% premium. If you choose to, that's your choice but, for me, it simply is not cost effective.