John,

Your budget limits your options, but there's hope.

Consider a Dahon P8; it mght fill your needs.

What and where is your arthritis?

We're the same age. My arthritis is primarily in my thumbs/wrists, but ergonomic bar ends make a huge difference. Flat bars are painful, but moving
to bar ends relieves significant stress. Takes some time to get used to them, since hands there mean a movement to brakes and shifter.

For what it's worth...