Currently, Wild Apricot is the recommended club and association management service by the U.S. National Rifle Association. As such, I personally have implemented it with three groups.
For credit card processing all three use PayPal. Based upon volumes two of them could save money by moving to another service, such as Payment Alliance International, another NRA sponsored vendor.
Unfortunately, Payment Alliance using e-processing network, which is not directly supported by Wild Aprioct. Best of all worlds would be to develop and deploy as an option the support for e-processing network directly. A second alternative would be to leverage Payment Alliance's Authorize.net emulator. There is slightly more expense to use the emulator, but it is only $5/month.
The alternative to use CRE-Secure, is cost prohibitive for a small organization (lowest is $40/month).