I just picked up some acrylic for a sump a couple of days ago from Plastic Supply on Candelaria (right next door to Coral Island).
For a 1/4", 24 gallon sump it came out to about $4/sqft cut (and took about 5 minutes).
For a zero edge, you might consider going with glass, since you'll probably be scraping a lot of coraline on both sides. Though I'm not really familiar with how zero edges are built...