Kesef Kiddushin - no background needed for this one

One of the ways a man can marry a woman is by either giving her money or the equivalent of money (like a ring). This is called kesef kiddushin. Kesef can also be used to acquire land and the gemara in the beginning of kiddushin, in fact, learns kesef kiddushin from a gezairah shaveh from land.
When it comes to the purchasing of land with kesef, there is a well known debate between the Sma and the Taz in Choshen Mishpat. (See the Birchas Avraham in the beginning of Kiddushin who brings the exacts source.)
The Sma is of the opinion that the kesef used to buy land should function as the techilas piraon, the beginning of the payment for that land. So, if you put down a dollar for a piece of land that dollar will not only create a kinyan on the land, but it will also serve as a down payment on the land. The rest of the money will be owed by the purchaser. The Sma's proof to this is that kinyan kesef is learned from the field that Avraham Avinu bought from Efron for money. In that case the money was not merely a ceremonial kinyan, but it functioned as payment as well. From there we see that all kesef kinyan should serve as piraon.
The Taz disagrees and argues that, in fact, kesef kinyan is merely a ceremonial kinyan and the money does not serve in any way as payment for the field. His proof is from the fact that the gemara compares the acquisition of a field to marrying a woman. In the case of marriage, no one would say that the money a man gives a woman is a payment for her! If so, we cannot say that the money one uses to acquire a field acts as payment.
In yeshivos in general this dispute between the Sma and the Taz is viewed as the classic "chakira" in kinyan kesef, whether it is piraon or a ceremonial kinyan. In fact this dispute is really only one nafka mina within a much broader chakira in kinyanim in general.
When it comes to kinyanim we can classify them into three basic categories. Most kinyanim, like meshicha, hagbahah and chazaka (pulling, lifting, or using the object being acquired) work because they are an act of a demonstration of baalus, or ownership, of the object. These are the most classic of kinyanim.
In the Birchas Shmuel in Siman 5 of Kiddushin, R' Boruch Ber points out that kinyan kesef works in a different fashion. It is not a demonstration of baalus over the field being acquired, but, rather, it creates a shibud. That is to say, the person receiving the money becomes "obligated" to the buyer because he received money from him. That obligation, or shibud, allows the field to transfer from the seller to the buyer.
Finally, the Birchas Shmuel points out that kinyan chalipin may fall into a third category. In chalipin, the buyer gives a basically worthless item to the seller, and by simply lifting the object, the field (or whatever is being purchased) is transferred to the buyer.
In this case there is no shibud because the item used for the chalipin is worthless. Also, the buyer is in no way demonstrating any type of baalus on the object. Rather, in this kinyan, the action of lifting the hankerchief (or whatever worthless item is chosen) is only to enable the seller to have the proper daas to transfer the item to the buyer. In other words, the kinyan is mainly effected through the daas makneh. The action being done is merely to concretize that daas.
With this in mind we can revisit the dispute between the Sma and the Taz. All agree that the kesef works by means of creating a shibud. The question is how directly is that shibud related to the field being purchased. The Sma argues that the shibud is directly related in that the money is the actual money being used to purchase the field. The Taz, on the other hand, holds that the shibud is unrelated to the payment for the field.