Agreed. Especially if you are at the beginning of your career (1-3 years into the job market) I would hold off on being too agressive with your salary negotiation…UNLESS you do in-fact have another solid job offer in writing from another company.
The expense document is a good place to estimate your life-style expenditures, however as YO mentioned it has no bearing to an employer. Perhaps the most important question ask yourself is; Do I want to work here? So you probably need to decide if you actually want to work for this potential employer and also try think beyond just the offer in front of you, understand how it will help you grow as a designer.
If this is a position that you can learn something new from, and gain new insights or a new/unique perspective, then it may very well help you in the future (perhaps 3+ years later) when you are ready to move on to the next chapter in your chosen profession. At that time you may be able to negotiate a higher salary and possibly ask for more/better benefits.