First of all, I think some of you are to quick to be jumping all over the seller here.
Any chance we can get this Rick guys opinion of the situation? If he knows what he is doing and knows how to examine a snake, then why did he accept the snake in the first place??? The way the OP spoke of this middle man, it sounded like he was educated enough to determine if the snake was healthy. If the snake was as sick as you claim, I think it should have been detected then.
If the OP was comfortable with the middle mans decisioin to accept the snake, then he needs to be held more accountable then some of you seem to think. This was a hand to hand delivery, not a site unseen over the internet. If the middle man thought there was something wrong he should of called the OP and said "what do you want me to do". At that time the OP could have said to refuse the animal and the seller would of had to refund his money. Some people have a policy of all sales in person are final.
Why wait a week before you picked up the snake from Rick? How do you know what the conditions the snake was in during the week in waiting? How do you know it was cared for properly?
If the OP is still willing to give you a partial refund, I think you should be more then happy.
There are two sides to every story, and in this case even a third.
In the case of the baytril, it is a prescription drug, yes. It is also one of the safer antibotics you can use. I knew a vet years ago, and if he knew you then he had know problem giving you the baytril. He even sold it at reptile shows.
I don't know how small of a needle you are refering to here, but it would not take a big needle to do the job on a snake that size. What your experience is with injections is also something we don't know about. But I will tell you with baytril, you want to go in under a scale at an angle right along the side of the back bone in the mussel tissue. You do not want to stick the needle straight into the snake.
In my opinion there are some things here that don't ad up.