You might be missing the point slightly too. What you'll miss out on smaller drive isn't just the capacity, but performance too. You may find the hit acceptable for the money saved, or perhaps that deviate far too much from your original budget, but one could certainly argue that it's better value long(er) term.
http://www.anandtech.com/show/3756/2...ake-on-intel/7
BTW, if you need so little capacity, then it doesn't make much sense to go hybrid. The latest hybrids are certainly competitive with high end mechanical drives (i.e. Velociraptor), but they still get murdered by SSD when it comes to random 4k performance. So if you don't need the capacity, stick with SSD.