47, according to the UCM.
e.g. a MOSC G1 Micromaster Patrol counts as four, a MOSC set of Armada Mini-Cons counts as three etc.

Almost all of these are doubles. I sometimes receive Transformers as gifts and if I already own that toy then I keep it sealed. I do occasionally acquire variants or doubles for the purposes of keeping sealed.
e.g. the Kmart reissue Mini-Bots and Wal-Mart reissue Cassettes are things that I keep sealed because I like the look of sealed G1 toys. I already have the original G1s and previous reissues loose, so I have no need to open these figures.

But yeah, my sealed toys are deliberately in that condition. It's not because I've procrastinated opening them; if I'm going to open a toy then I usually do it almost immediately after purchase. Some of you have seen the Toy Emancipation Kit that I carry with me. I should also point out that these are 47 toys in a collection of 2451, or 1.9%. So yeah, 98.1% of my Transformers are definitely emancipated. I can't play with a sealed toy, and I have loose versions of all the sealed stuff I have anyway.