I don't mean to rain on your party but if you take out the wall w/o doing some of the 'right things' along the way (like supporting the floor above while you do the demolition), you'll be in waaaaay too deep with your insurance company trying to explain to them you KNOW what your doing. You could easily lose the claim through negligence.
If you want to save $$$, get a bonded and insured contractor (ask for proof on paper), and have them do the rough work first. THEN, you (and whoever) can do the finish work like hanging the drywall, installing installing the trim, and so on. I've seen the worst case scenarios. There are building code issues, and believe me, if you mess up, you'll regret ever embarking on such a job. That's my advise.