I did chemo for my Louie, but that was a long time ago, back in '99-2000.
I don't remember specifically how much it was - I remember the meds were different for each treatment, so they weren't always the same price. It was probably about $100 per treatment.
Have you done any research about Chase's condition? There's some discussion of the similarities between lymphoma and IBD (Inflammatory Bowel Disease is the proper name; I had mistakenly been calling it Irritable Bowel Disease or Syndrome). I didn't realize it, but apparently lymphoma can only be definitively diagnosed with a biopsy. There are different types of lymphoma, high and low grade. Each has a different prognosis.
I'm glad Chase seems to be perkier - the food is certainly helping him. If he'll eat from your finger, that's fine, as long as he eats. It's good that you're continuing to encourage him to eat on his own, too.
You might want to try other canned cat foods to assist-feed Chase. The A/D is ok for the short term, but they've changed the formula. Pork is one of the major ingredients now, which isn't great for cats. I think it contains corn too, which can be tough for some cats to digest. You can try Wellness, which has many grain-free flavors, and is actually higher in calories than the A/D and higher quality. I use it to assist-feed my cat. The chicken flavor has 220 calories per 5.5 oz can compared to the A/D which contains 180 calories. My vet has told me that the average cat needs 200 calories per day, with ill kitties usually requiring even more.
Digestive enzymes might help. I've been using them for a long time now. There are lots of brands available - I use Prozyme.
If Chase is constipated, try mixing about 1/4 teaspoon *plain* (no pie mix - it has spices) canned pumpkin into each meal. Cats usually like the taste. Most times the kitty will feel better in a day or two.
About the B-12 : try to get the vet to sell you a bottle of it, even if you won't be doing many B-12 shots. If she sells it to you per syringe, it will be more expensive, about $10-15 per shot. You should be able to get a bottle of B-12 for about $10.
I think the "green plastic thing" you see in your sub-Q fluid line is an injection port. It should be shaped like a "y" and have a little cap on the part that protrudes off the main line. That's where you'd administer the syringe of B-12 - right into and through the center of the cap, where you'll see a tiny circle.
You have to make sure to give some plain sub-Q fluid first, at least 1/2 the amount you'd normally give, then inject the B-12 into the port, then run the rest of the fluid in. The reason to do some fluid before the shot is that B-12 can sting unless it's given into a little "pocket" of fluid.
If you want, I can give you the name of the company I buy my fluid supplies from. They sell by the case, 12 1000mL bags. You can also get syringes for the B-12 shots, and assist-feeding syringes too. It is *much* less expensive than buying them from your vet.
Fingers crossed that Chase continues to eat and improve