What do you have on the top of your tank? Is there something there to block the viewing of an eggcrate cover? If so, eggcrate would be an inexpensive option.
If you are running a rimless or just a sleek light fixture on top (no way to hide something as thick as eggcrate) then you may want to look into picking up some pexiglass or glass and cut it to size. That'll give you a streamlined design and if you do it right it'll be less expensive than buying from Dr. F and S.
I built a top for my 55g for $40 and that was buying from Lowes (more expensive than someone who specializes in acrylic). Most acrylic warehouses will even cut the plastic down to the correct size for free (or a small fee...but it's well worth it if you don't have the right equipment).
Here's a picture of my tank so you can see what I'm talking about. The acrylic sheets sit inside the top frame. It's fairly simple to cut slots for wires/tubing in the back too.