One of the things I forgot to mention in the first post, which I can't edit anymore. There are two types of coins. Golden ones, naturally, are the most valuable and called sovereigns (gee how original), silver coins are just that, silvers. One sovereign is worth 100 silvers (why try to reinvent the bike?). For one sovereign, you can eat lavishly for a week, or if you don't want anything fancy, you would have enough money to last a month. For ten, you can buy a horse which is a huge luxury. 

The mysterious employer will offer quite a bit more than that. Rumor goes that he will pay 25 sovereigns for the job.