I am sorry for everything that you and Buddy have had to go through the last few days.
I know there is some concern as to what went wrong and whether it was the vet's fault. Without being able to see neither Buddy nor his chart (and not having been there) it is impossible to say. I will however give you my observations from what I see. Short answer: Such complications can occur under the best of circumstances.
Let's start with what is normal or at least common.
1) The scrotal hematoma is not an uncommon complication in adult dogs. Most dogs do not have this occur but some dogs appear predisposed to it. Luckily, time will take care of it. Cold compresses help.
2) The prescrotal incision in the picture appears consistent with a reclosure of an incisional site. The edges are not aligned or perfect, but when the incision has come open and needs to be reclosed - this is how it will look.
What is not common.
1) The prolonged recovery is unusual. Most dogs are fairly "normal" the next day and our biggest problem is usually keeping them from bouncing off the walls like normal. With that said, some dogs have a more difficult time with anesthesia than others. This unfortunately occurs can happen no matter who the vet is.
2) Fees 50% or less than other vets. Quality medications, surgical supplies, equipment, etc. costs money. "A cook can only be as good as his ingredients." There are many possible legitimate reasons but that is a drastic difference.
A couple of questions:
1) Was an IV catheter used to provide fluids to Buddy throughout both procedures?
2) Was pre or post anesthetic blood work performed?
I hope that this experience with Buddy does not steer you away from neutering another dog. Buddy's experiences are not typical. These type of complications can occur with cats too. It is important to remember that these complications (prolonged recovery, hematomas, second surgeries,etc.) are not likely and usually do not happen all together. All of these complications do happen with all vets and sometimes in combination - the key is to keep them as rare occurrences. If you have more information, I will be happy to look at it.
I am glad that Buddy is feeling better. Keep us posted.