One should always assume they have the most common type.
Oh come on John Becker, someone wins a lottery everyday, even the phillatelic lottery. Remember this very recent SCF thread: http://goscf.com/f/15
Some people play for the biggest mega-millions prizes and other the lowly low value scratch-offs. Clearly nandu1001 goes for the big prizes. Sending in an 85A on-cover for a certificate is a bit pricey, not the certificate fee, as those are usually set at the minimum for unlisted or unpriced in the catalog items, it's the postal insurance on a $5,000,000.00 unique item which can be steep especially if one pays only one way.
What to do, what to do...
The SCF is free.