Since you are already following the Clark protocol, if you want maximum in an econo-zapper build your own following the instructions and parts list found in Hulda's book - The Cure For All Diseases
(reprinted as recently as 2004). The book costs $21.95 plus or minus shipping and or any discount offer you may find; the parts can be acquired for roughly $20 to $40 at an electronic supply store; these instructions comprise a solderless approach that she fashioned specificaly for those who are not electronically inclined.
The book, as well as Clark's products - including her most recently revised model of Zapper that sells about $190, can be found at her products site:
As an alternative, here is a link to a product that is based upon the Clark design but it uses a lower frequency (15Hz), uses simple electrodes (pennies) instead of hand-holds (so it can be used/placed on many places of the body), does not have all the user-selectable modes like the Clark design (only two modes: on; off), but does include a mobius-wrapped plug of orgonite, and costs about $130.