You could offer to clean the bathroom, shovel snow, rake leaves, water the garden, make the beds, do the dishes, wash the car, clean your room, or organize shelves/cabinets.
You can offer to tend or water a garden, clean their pool, clean the patio, rake the leaves, or shovel snow.
Save up some extra for your first payment(s) on your future phone.
The advanced search option found on most sites can help you find a phone in your price range, and the type you want (flip, slide, touchscreen, etc).
Keep the size of the phone in mind - a man can fit most sizes in his pocket, but a woman who doesn’t wear a purse will have to pick a phone that fits in hers.
Depending on how tech-savvy you are, the ability to use a phone varies. You might want a simple Nokia phone or an iPhone, depending on how well you think you can adapt to using it.
Don’t sneak around your parents’ back and buy a phone - there’s no way they won’t notice!
If your parents are mad or busy, don’t pull them away for the presentation!