It's been publicly stated (somewhere) that "The Bitcoin Trust" will need to purchase bitcoin beginning with the very first investor. That initial $2.5 million does not cover the first $2.5 million in investment from outsiders, but was just to "get the fund started".
With that having been said, yes... at some point the Trust will need to purchase bitcoin when investor money comes in. It isn't a question of "if" but rather "how much" and perhaps "when" (I assume whenever they invest). I think Barry stated he's made relationships with exchanges and miners, so he may buy at least some of that directly from miners. In that case, it would be indirectly observed on the exchanges.
they should buy the FBIs bitcoins
![Tongue](https://bitcointalk.org/Smileys/default/tongue.gif)