In terms of cost, my advice... especially if you're on a limited budget.
Figure out how much it cost to rent equipment and add that into your prices.
In terms of owning equipment of your own, buy quality stuff from the beginning. Like if you have enough money to buy a 5D Mark III or 7D, then get it.
Its either that or save money so you can get get quality stuff...
Because you don't want to buy equipment like a t2i, and then a year or 2 later you want to upgrade... then you're selling the t2i for half the price you bought it for (losing half the budget that you used to purchase it)...
Till then, rent!
I forgot to say... more than just camera equipment.... look into getting good post-production equipment.
Cause you have to know... especially with video production, most of the time you'll be spending it in front of a computer.
I'll second that heartily!!
I started out my editing with FCPX, which works pretty well on the mac and is dead cheap compared to other alternatives.
And if you're not used to editing in the more traditional track based editors (Premier, Avid, FCP7), then the learning curve is quite low.
I've recently gotten a deal (I applied for admission to a local university, just to get a .edu email and picture student ID, to use to get educational versions of Adobe products, but not planning to enroll in any classes), and just got Adobe Production Pro Suite (CS6)...(I'm not going CC, don't want to rent software just yet).
Anyway, I've been trying to learn Premier and After Effects.....very powerful stuff. A bit more of a learning curve, but wow..neat stuff you can do with those.
Also, once you get going, you might want to play a bit more with color grading, to give your videos a "look". There is a very powerful, free program called Davinci Resolve Lite. Very cool tool.
You need some horsepower in your editing computer...so, do a bit of research which ever platform you go with (mac or pc)...
The new mac pro, when it comes out, is likely to be a VERY nice editing tool.