Questor,
A minor point, but Optima 2000 sights which were manufactured by Tasco are no longer made since Tasco is out of business. The same (or very similar) sight is made by J-Point, and IMHO, they seem to have fixed many of the problems that plagued the early Optimas.
Unless you can find a used Optima, any new purchase will likely be a J-Point, which are carried by a number of internet retailers. Regards.
Sawfish