I would just add something to what the minister has just said.
If you go out for requests for proposals, the more official process, knowing that there is likely only one supplier who can meet the need, you are then obliged to accept any bid that is put forward, which could be quite a rich one. In other words, you can't negotiate from that point forward, so you could end up paying a lot more than you need to.
If you know there's only one supplier, the answer is to scan the market first of all, as the minister has said, to find out if there's anybody else out there. In that sense, it is not a sole source, it is an open process. If somebody does come forward, you go into a full RFP. If nobody comes forward, you then have the opportunity to negotiate hard with that supplier, inasmuch as you can say you won't buy unless you get a good price, first of all. Secondly, you want to know what their profit margins are, how they compare with what other buyers are paying. So you have leverage because you don't have to sign the contract. If you go with an RFP and there's only one supplier, then you're just stuck with whatever they propose. That's why you would do this in this other fashion.