You should be able to order all of them from PetSmart.com or Amazon. It may not hurt to take everything down and clean it in white vinegar, then soak it in clean water and rinse well. That will get rid of anything stuck to it, while not being harmful to fish if you don't get it all off.
Also, I prefer Stress Coat to Prime, just because it dechlorinates, removes heavy metals and helps with the fish's slime coat, if you're dealing with well water, that may help and you may want to think about filtering it too in a Brita or something.
Those numbers are a bit high, the pH especially. I would get a pH buffer, and do a water change. I would look at your Petco/PetSmart and see if they have the API Quick Start - its a bottle of beneficial bacteria that "instantly start your tank". I usually get it and do a dose about 3-5 days...
Sorry about your loss, but we have all been there! Can you run the water test again and post your levels on here? We can't really help you out without knowing what is going on chemically.
So I had 4 Waken Goldfish in a 45 Gallon tank - They are all 4-5" in size and will be transferred to a pond when they outgrow the tank. I went away for a night and came home this morning to find one of them floating upside down with a black distended abdomen and it's mouth apparently "stuck"...
Yeah I'm not planning on them outgrowing it for a while lol. People on this site like to yell at you for overstocking and not thinking ahead, so while it may be years out, they need to know I have plans haha.
I'm sure that is a possibility. If the medication you're using isn't working, I would try some other anti-bacterial medication. If those don't work, it's probably a parasite. Good luck!
It's a floor level 45 gallon. I have 2 family members with huge ponds for when they out grow the tank haha. My Leopard Gecko is in a 40 Gal Breeder above it, almost the same footprint length wise, so the stand works haha.