$535 with Fleck 5600 valve and gravel bed (not quite as confident in this company)
$620 with Autotrol valve and gravel bed
$649 with Fleck 2510 or Clack WS1 valve and Vortech distributor
$670 with Clack WS1 valve and gravel bed
$1218 with Fleck (non-electronic) valve and gravel bed, includes installation (quoted by local dealer)
I am leaning towards the Clack valve, and it appears I can get a system with it cheaper if I go with the Vortech system. Of course, there are issues of after-sales support and the like, which are hard to discover before the fact. And maybe I just have not found the company offering the best deal yet...