Greetings,
Been doing some research, and have to agree with all the others here. Your 19" TV screen is too small to be able to see the guide clearly. Screen-size is everything in the OP's case.
As he is dealing with a small apartment, potentially limited income, and a confined space, I would recommend this Samsung TV I found at Best Buy It's a bigger screen (32 inch), HD, and it will help most definitely with his vision difficulties. It's under $300. Consider getting it and see how it works with your Roku:
You will notice a difference right away, I promise. You will also need an HDMI cable if you don't already have one to get HD. They run about $20. Do you know anyone who could get the set and HDMI cable for you? This is your best option for sure. I have had a Samsung set for years. Really good!
To confirm, you will need a Spectrum cable box if you want to order the Big Button remote. I would really consider this TV in your situation. You need a bigger screen at an affordable price, and something that will fit in an apartment space,
Satch