Sorry to hear about Patches infected eye. I really hope you get out of this rather quickly. I agree with Mrs_Savas. I wanted to add that there is a website called 1800petmeds which offers the same meds you'd get at the vet a lot more cheaper. The only problem would be the time it takes to arrive. So, it'd be best to take Patches to the vet right away, get a list of all the meds you have to give him if you can't pay for it, and then order it on petmeds.
Good Luck.
It does sound like an eye infection. They are incredibly common in kittens and can cause a lot of damage if left untreated. The good news is that they are easy to treat with oral antibiotics and, sometimes, a topical opthalmic (eye) ointment.
The best advice that I could give you would be to ask about the price of medication(s) when you ask about the price of the visit. These cost do vary from vet to vet and from location to location (for instance, New York City, where we are, is very expensive, while just a short way from the city is cheaper). Do your best to find a trustworthy vet, not just an inexpensive one.
There are websites that sell discounted pet prescription meds - you see your vet for the prescription which is transferred to the online pharmacy. Unfortunately, best case scenario, it will take a few days for the antibiotics to arrive by mail, so it's not a good idea in a case like this where your cat needs the medication right away. But it could be something to look into in the future, for meds that you need regularly like flea drops
Has Patches been neutered and had his tests and shots? If not, it's really important for his health and your peace of mind (you don't want him to start spraying around the house, for example). If not, perhaps you can ask around about those costs as well so that you can plan for the near future.
I know it's tough - it sounds like you know what to do and are doing your best.
Please let us know how your Patches is doing and don't hesitate to ask other questions.