An exercise or stability ball, costs about $15+. Make sure you get the right one for your size leg/weight. Make sure it is the right size or you won’t feel comfortable using this.
Dumb bells are good for a home gym, you can choose a lighter weight and a heavier weight to get started. It is easier to add to this when you get fitter.
Exercise bands/ropes come in different strengths and it is easy to pick up a multi pack in a big box store for $15.
You need a cardio machine that you will use. Do you like treadmills? How about the Elliptical? Or just go with a mini re-bounder for $30+ and step for cardio.
Work out videos or on demand tv or local trainer classes are a good bet to give you a good all round workout, getting all the major muscle groups.
For intermediate level you may enjoy:
An adjustable bench is a good idea, even if you aren’t a big weights person, a versatile one can be used for leg lifts, and incline. It can cost $40+ secondhand.
A chin up bar can be a cheap and easy to install in the frame of a door but make sure it is installed correctly as you may get hurt if not.
Look online for workouts, there are many but check with your doctor first.