Hi Joel,
Having grown up in the suburbs of Paris, I may be able to give you a hand about how much it may cost you.
1st, housing cost is usually high in Paris itself, and still quite high in the first circles of the suburbs.(Even in the last ones considering some much smaller cities...) In paris, count 700€ per month + Charges in order to get a 15m² room for yourself. You may be able to find at lower price, but consider lower prices as a bonus. If you stay more than 3 months, you will still be eligible for the APL/ALS, which is a housing help from the French government. Count around 200€ max per month.
After, for transportation, you may find prices there: http://ratp.fr/
For food, etc... Prices may be a bit higher, especially considering there are not so many very big supermarkets in the city. Going out is also expensive, a 25cl beer being in my memories around 5€ usually.
Well, you can PM me if you want to talk more precisely about your plans.