According to my math...you need
(6) 88 OVRs, which cost about 250k each to build - thats 1.5 milly
(4) 89 OVRs, which cost about 400k each to build - thats 1.6 milly
(2) 90 OVRs, which cost 500 k each to build - thats 1 milly
Total cost is 4.1 milly - you sell all card on auction house and get 3.7 milly back - lose about 400k
But get a 90 OVR - and your pick
Top most feared 90 OVRs are going for 600k