Nothing cheap, are you really slot limited? And if you are going to do VT-d do you really want to pass all 4 to the same VM? Thats how it will normally be, the other cards with onboard pci bridges usually won't pass cleanly.
A pair of very common (server pull) intel dual ports would be maybe $70 shipped.
Nearly dead silent HTPC ver 2.0: i3-4340 w/ Noctua NH-L9i on Z87E-itx inside CM130 elite, fanless PSU, SSD OS drive
SAN shares via 40GbE tunneled over 56Gb infiniband links
microcenter & ebay = severe risks to my wallet