You may want to verify that your sponsorship system is working without spending money. For 2checkout and authorize.net, you can do this just by enabling the testpayments tweak at Admin -> Settings -> Tweaks Editor. Testing payments with PayPal is a little more complicated, since they require using their distinct sandbox area. WSN simplifies this for you as much as possible. Follow this procedure:

1. Login at developer.paypal.com
2. If it doesn't offer to automatically set up personal and business test accounts for you, create a personal account (test user to pay) and business account (test user to sell) and confirm your emails for them via the "email" tab of developer central and add a credit card (use the default credit card info it gives you).
3. At the WSN admin panel, Admin -> Revenue -> Sponsorship, enter the corresponding email for your test business sandbox paypal account.
4. At Admin -> Settings -> Tweaks Editor, enable the paypalsandbox tweak if using version 8.0 or earlier, or the testpayments tweak in WSN 8.1 or later.
5. Do your test purchases. Note you have to be logged in at developer.paypal.com in a background tab while testing trial payments.
6. When done, be sure you turn off the paypalsandbox/testpayments tweak and re-enter your proper live payments email at Admin -> Revenue -> Sponsorship.