I thought you could go either HDMI+DVI+DP or DVI+DVI+DP. if not then you could allways use a pasive DVI to HDMI converter if you realy needed HDMI.
The cheapest ones ive seen are at $100. heres that dell one:http://accessories.us.dell.com/sna/products/Cables/productdetail.aspx?c=us&l=en&cs=19&sku=330-5521
other rebranded ones ive seen are from amazon and sapphire.