You must register and take the CompTIA exam prior to the expiration period of each CompTIA certification voucher. You can buy your CompTIA voucher directly at http://www.comptia.org or http://store.comptia.org/shelf.aspx?shelf=3. You can avail of the CompTIA voucher at a special introductory price which is the CompTIA member price, or the non-member price.
The CompTIA voucher comes in two classes: as the Thomson Prometric (a subsidiary of Thomson Corp.); and the Pearson Vue (which is owned by the British Pearson PLC.) Currently available here would be the Comptia vouchers from the Thomson Prometric, as of 2007. These are the CompTIA PDI+, A+, Network+, Security+, Server+, CTT+, CDIA+, CEA-Comptia DHTI+, Linux+, Project+, RFID+, and the Convergence+.
The CompTIA PDI+ Prometric voucher (which expires on April 30, 2008) is available in pre-order at $168 for members and $199 for non-members (for United States and Canada purchasers.) The CompTIA A+ Prometric voucher is available at $128 for members and $163 for non-members. This can be used by for the A6 Essentials 220-602 (IT Technician), 220-603 (Remote Support Technician), and 220-604 (Depot Technician) of North America only.
However, the CompTIA vouchers including Network+ Prometric, Security+ Prometric, Server+ Prometric, CTT+ Prometric (which is the valid for CBT exam only), CEA-DHTI+ Prometric, Convergence+ Prometric, Linux+ Prometric, and Project+ Prometric are all available at $185 for members and $ 232 for non-members of North America only. Likewise, CompTIA vouchers including RFID+ Prometric, Security+ Prometric, and CDI+ Prometric are available at $ 202 for members and $251 for non-members (for North America purchasers only.) All of these vouchers except of CompTIA PDI+ voucher will expire on June 30, 2008.
On one hand, the counterpart vouchers of Pearson Vue come in prices and expiration date similar with vouchers of Thomson Prometric, as well as its locale availability. Prices, expiration, and locale availability of CompTIA vouchers are updated every now and then. It is advised for you to visit shopping sites of CompTIA to get updates of the CompTIA voucher pricing.