The standard monetary system is decimal, as follows:
As a very rough guide to the value of money, assume that a penny is worth about a dollar. The most common coins in use will therefore be pennies and shillings, with the occasional mark and very, very rare gold crown showing up.
This is, admittedly, a very simplistic monetary system which does not reflect actual medieval practice. However, the thought of trying to work out prices in ha'pennies, groats, farthings, thruppenny bits, shillings, florins, half-crowns, crowns, pounds, guineas and marks just gives me a headache.
Since the facilities for mass-production do not exist, most consumer goods will be substantially more expensive (relatively) than their modern-day counterparts. Things such as clothes, tools, weapons and so forth are very, very pricy, and are made to last.
Services, on the other hand, are cheap. A good meal and lodging for the night at a decent inn, for example, will be likely to cost somewhere in the region of a couple of shillings.
Wages vary (as always) depending on the availability of labour. An unskilled labourer will be lucky to make more than a few pennies a day unless there is a serious shortage of workers for any reason.
Livestock varies wildly in price. It would be possible to buy an old nag on its last legs for a few shillings, while a pedigree warhorse might cost a hundred crowns or even more.
For example: In 1450, it cost roughly the same to outfit a knight with horse, weapons and armour as it would cost nowadays to buy a state-of-the-art Main Battle Tank (taking into account relative monetary value). Many noble families put themselves and their descendents deep into debt to buy the latest fashions in military accoutrements. In medieval London, the second-hand clothes dealers were one of the most powerful commercial interests in the city, and a suit of clothes would go through five or six owners before finally being condemned to the papermakers' vats. Tools were also very expensive; a newly-qualified journeyman carpenter would expect to pay a year's income for a reasonable set of woodworking tools.