The budget will all depend on what size the product is, what you’ll need and how much time it is going to take. A schedule will need to be created with the client in order to make sure that the product can be created in that certain amount of time. The budget will also depend on what equipment you’re going to need. If you have to purchase more software in order to do what the client wants then that will need to be taken into consideration. If you’re working for a company then you probably will already have the software that you need available to you, but when you’re working on your own then you’re going to need everything yourself, unless you can find someone that will do a certain element of the product for you.
If you are a professional then you can charge the client a lot more than what you could if you were a student. Clients won’t be willing to pay a student the same amount as what they’d pay a professional. When you are first starting out working with clients it’s a good idea to get a job and work alongside a professional. Allow them to pick up all of the profit but work with them along the way to pick up skills and experience for when you’re on your own.