How would the buyer go about it? Was it usually between the buyer and the seller, or were there intermediaries like lawyers? Would a bank be involved? Would the whole sum be expected up front, or would it be spaced out like it is today?
Also, how were large cash transactions managed in cultures that had no paper money? Spaced out over time to make up for the difficulty and lack of security of hauling around large amounts of coins? Did the people just assume that large transactions meant bringing extra servants and guards?
ETA: Ack! It seems that I've asked the wrong questions. I'm writing about a secondary world that I'm basing very roughly on 17th-century England. From your extremely helpful advice, it seems that the real English housing market of the period was full of complications and variations that make an accurate historical answer difficult. I'm not looking for a history-quality answer, though, just a general idea of how much a house was worth to buy or rent in an economy similar to 17th-century England.
The house itself is a small townhouse with no land but a tiny back garden. It's richly decorated, but only the immovables come with the house--mosaics, murals, etc. It's located on the edge of the university district.