I now have a router (free) and a router table ($20), and a flush cut trim bit ($17). I have the next little test tank rough cut with the table saw (acrylic scrap was $17), from the scrap pieces I used to get the router fence square it makes a VERY nice edge. Should be about 10 gallons.
This time I'm going to do some things differently. One, I have some colored acrylic; Acrylite FF. I believe that is continuous cast and not extruded like the other stuff I was using. Falls between cell-cast and extruded as far as density goes (cell being the most dense). I have one piece of extruded, it definitely cuts differently than the FF. Second, I'm routering the edges and then wet-sanding them. Lastly, I'm not going to flame polish until the tank is all together and then just do the visible edges.