There are a lot of good replies here regarding the economics, but they've all missed a rather simple and glaring cause of the disparate price: a house was a far simpler construction back then. In 1300, most houses were single story, single room buildings. The walls were simple wattle and daub (i.e. mud and sticks) supported by a frame consisting of a few rough hewn beams of timber. Metal tools were scarce and expensive, so the timber would be split using wedges and sunk directly into the ground (no foundations or basement). There were no chimneys or fireplaces, perhaps only a hole in the thatched roof above a simple stone hearth. The floors would be packed dirt covered in rushes.
A house like that wouldn't meet any of the minimum legal requirements for fire code or habitability in any modern society. Not by a long shot. They're much less comfortable, safe, fire resistant, well lit, large, insulated, private, secure against intruders, and hygienic than modern homes. There's no plumbing or electricity.
All of the raw materials were freely available from the land within half a day's walk of the house. No need to mine iron ore from Australia, ship it to China to refine into steel and shape into hinges. Just tie a rough board over the doorway with a leather thong. And this kind of house could be thrown up in a day or two by a relatively small group of laborers who wouldn't need any specialized skills not generally shared by all members of the peasant classes.
They would also hold up less well to harsh weather, requiring more frequent repair and replacement than a modern house. You could expect near total depreciation on the order of 5-10 years, much more comparable to a modern car than a modern home.
Lastly, demand for urban housing and land was significantly lower in the 14th century. This era far precedes the development of native British textile manufacturing, the first urbanized large scale industry in England that created a demand for centralized labor pools. Most large cities were cathedral or market towns, meaning they were centers for intermittent trading or religious activities, not fixed industrial production areas requiring large warehouses or factory buildings or large labor pools. Thus the populations were extremely small, only amounting to perhaps 10% of the total population of medieval England. York, for example, had a population of around 20,000 in 1300. Land and housing was correspondingly cheaper.
So: (1) significantly lower quality product, (2) much lower raw material and labor costs, (3) faster depreciation of value, and (4) lower demand all contributed to a significantly lower price than in the modern era.
You may hate this world, but believe me, if you knew how people lived in 1300 in York, you wouldn't want to buy a house there.