I gave you two layout options. I know you said you wanted the desk in front of the window, but I thought the sofa fit a lot better in the space if it was along the window wall. I also went a bit over budget, you needed a smaller side table to fit with the sofa, so that's what threw me off ;) If you decide not to go with the side table you'll be able to afford more accessories. Also in the layout with the sofa along the windowed wall, you won't need the mirror, so that will help give you more breathing space with the budget.
PILLOW OPTIONS
pillows for sofa (2) $84
RUG OPTIONS
gray rug $172
tan rug $60
LIGHTING OPTIONS
pendant $64
table lamp $80
desk lamp $49
DESK
desk $210
CHAIR OPTIONS
desk chair $153 (use code WM1504)
desk chair $199
BOOK CASE OPTIONS
metal shelves $269
shelves $250
CABINET OPTIONS
file cabinet $196 (use code WM1504)
silver cabinet $200
ART OPTIONS
8x10 painting $90 & frame $10
painting $216
painting $55
painting $77 (use code WM1504)
MIRROR OPTIONS
captains mirror $81
starburst mirror $140
SIDE TABLE
TOTAL
$1,526
MIX + MATCH ACCESSORIES
agate bookends $58
fleur de lis box $19
black glass knot $20
PAINT