Bannister said they had sent out video footage of Viljoen in action to the other associations after the professional was not introduced to the Devon Hotel Central Stags lineup for their Plunket Shield games.
"I got him to Wanganui because he was referred to me by Central Districts management. He was of the understanding he would have an opportunity to play 4-day cricket for Central Districts.
"The verbal facts were different. The facts were, Christi would have to go through Chapple Cup and Hawke Cup to get selected. We decided, we're going to put him on the market to see what it leverages."
The Volts and the Wellington Firebirds expressed an interest.
Viljoen will be leaving New Zealand on April 16 to resume his contract with the Blackpool club in Lancashire.
Whether or not he plays for another province between now and then, which could change his priorities away from Central Districts next summer, Bannister said Viljoen "absolutely" will appear for Wanganui in the Chapple Cup 50-over tournament, which is played between CD's minor association teams on the first weekend of the season.
"His goal always was to play first class cricket as soon as he can, so he would be in the same boat as [Wanganui's] Ben Smith."
Smith will be making his comeback from injury to open the batting for Central Districts against Canterbury today in Nelson.
He also plays for Wanganui on the Chapple Cup weekend but since becoming a regular fixture in the Stags lineup is not available for the Hawke Cup campaign or local club matches.
The Stags and Volts sit on top of the Plunket Shield table with three rounds remaining.