Arsenal spent big on Lukas Podolski and Olivier Giroud early on and splashed £12m on Santi Cazorla but finished around £9m in profit after selling Robin van Persie and Alex Song for a combined total of around £39m.
The AST say the majority of fans in their group backed Wenger in their end of season survey but claim a final judgement will be made on the pitch.
An AST spokesman told the Mirror: "Our own analysis of Arsenal's accounts shows the club have not used nearly all of the resources available to them to strengthen the squad this transfer window.
"Many of our members are extremely frustrated as they believe no stone should be left unturned in trying to make Arsenal a better team.
"As ever in football the final judgement will be results on the pitch."