Yes that’s not much of a price. Yes the difference is some century’s but did the price of a cottage really changed so much? We can also talk about price differences in regions. Maybe you could get a luxury cottage for 6 pounds. Or a crappy one for 1 pound. There are many variations but you could get some cottages for the price of an armor.
Also please take in notice we are talking about a smith in Czech lands. I doubt he will earn as much as an mounted archer on an campaign.