Why rely on a site to sell you a certificate when you can make your own these days? do you have a laser printer? just buy some paper and use a text program to make a copy of you own certificate and just change the names and print. 
Here is my story on this subject:
A few years ago I took my friends birth certificate down to the dmv to get a state id. Well......I was tripped up by the clerk when asked a couple simple questions about the certificate. I didn't bother to remember anything about what was written on it. When asked what my mothers maiden name was I didn't know. Then the clerk asked what my mothers name was and I DIDN"T KNOW!!! For some reason I knew my friends moms name, but I didn't tie the two together because I was so freaking out at this interrogation!
The clerk called over the security guard. I was escorted to the back room and the city police were called. I was busted and had to appear before a judge and sentenced to 30 days in county jail, put n 1 year probation
live and learn.