Alfred the Great ruled the Kingdom of Wessex for almost two decades towards the end of the 9th century. He defended his realm against Viking raids, and initiated vast reforms of his kingdom's military and economy.
Trever Ashmore has produced fake coins for over four decades and is still going. He is known for his counterfeits of medieval English coins.
Even for Alfred the Great, there seems to be at least 10 different types fakes by Ashmore, including the types with a bust, a monogram, or 'EXA' with dots on the sides. One of the types are shown here. They all have roughly the same look, though it can take a while to learn to spot them. Genuine coins from the 9th century, not surprising, are very valuable. Numismatic (coin collecting) research, experience, and 'trained eyeballs' are necessary to sort the counterfeits from the genuine.
Perhaps due to the fame of the counterfeiter, the Ashmore fakes are being bought by collectors at exorbitant prices (read: a few tens of US dollars). The truth is that they are fake coins made in modern times, and any value they have due to scarcity could quickly be ran into the ground by Ashmore simply making more of them.
The side-by-side comparison below shows a genuine Alfred penny next to an Ashmore fake. You can see that while it may be difficult to use 21st century technology to reproduce the look of 9th century coinage, it is certainly not impossible to do so. The genuine coin in this picture comes from highly respected Davissons Coins in Minnesota, USA, specialist in ancient Greek and Roman coins, and coins, tokens and medals of Great Britain. The genuine coin sold for $3500 US dollars in a 2014 auction.