Here's something to start with. I just sort of pulled out products with good reviews and such so I'm sure you or others can find other stuff that'll work as well. So consider this more of a starting point of researching prices.
Things like keyboard, mouse, and speakers aren't included as that all depends on what you want and/or have. For example, I use a Logitech G5 that I've had for a while, a 7 year old keyboard, and a used set of Logitech 5.1 speakers that I got for half the retail price at the time. Heck, I've also been using my DVD burner and DVD-Rom for years as well. Might want to include some thermal compound in there as well.
I'm going to try to copy and paste of the products I put into Newegg's cart. Taken from US Newegg site.
$1,279.88 not counting shipping of course.
Essay Pro