Don't rush into it. I think a Mr. Beer kit is great for people to give as gifts, but if you already think you want to brew beer, then read up on starter kits and find out what you can make do with at home.
Here is what I think you need to get at a minimum, to get started at home:
Something to boil your wort in. Large stainless or aluminum pot.
Fermenting vessel. 5 or 6 Gallon food grade bucket with sealing lid (with hole in top for airlock)
Airlock and bung.
Something to measure wort temperature, like a cheap (but reasonably accurate) thermometer).
Hydrometer (ok, you don't NEED a hydrometer, but without it you might not know when the fermentation is actually complete.
Personally, if you think the process of making beer sounds interesting, or intriguing, then I'd start with 5 gallon batches on the stove using extracts (I prefer Dry) and do it right.
Maybe look this site for videos of people brewing. Some of us have posted them.
If you are SURE you want to brew (and why wouldn't you), and can spare the $100 bucks now, then go get a kit from the brewing supply store of your choice. Yeah, you could spend less scrounging stuff up, but you'll be thanking us later if you just have the basics you need to start with.