Yes, this is most definitely permissible. Most church sales often benefit charity. If you are purchasing from such bazaars, then you are contributing to charity. On the other hand, if a church is knowingly sponsoring a political candidate or political cause that runs counter to the tenets of our Faith, then this would be problematic and we should refrain from such purchases.
In the U.S. it is not permissible for tax-exempt religious organisations to become too involved with politics, especially when it comes to raising money for a candidate. This often results in losing their tax-exempt status. This occurs quite often in the U.S., especially during presidential elections. No institute of the Church should sponsor political programs within its facilities.