National Public Seating 6424HB Grey Steel Stool with Vinyl Upholstered Seat Adjustable and Backrest, 25"-33"

It's surprisingly cheap/easy to put the whole thing together with things from Amazon and IKEA. For example:

    4x Olov 36" legs [1] = $60
    1x Linnmon 47" x 24" table top [2] = $20
    whatever small shelf will fit your monitor(s) = $20
    1x Adjustable Stool [3] = $85
    Total = $185

Just be aware of the heights. If you're over 6' tall, you'll probably need to put the desk on a $10 set of bed risers (or spring for the $30 Gerton legs that adjust over 40") and you may need the 6430HB stool instead of the 6424HB. The price on those should be within $5 though.

[1] http://www.ikea.com/us/en/catalog/products/30264301/

[2] http://www.ikea.com/us/en/catalog/products/00251343/

[3] http://www.amazon.com/National-Public-Seating-6424HB-Upholst...