The best way of finding out HOA amounts is to call the property manager that administers the complex and inquire on not only the dues but the overall financial health of the housing association.
A large number of HOA's throughout the country are still recovering from the housing crash where condo and townhouse owners walked away from their units and ceased paying the HOA dues, forcing the associations to spread the missing dues amounts over the remaining owners.
Some condo complexes in Southern California are known to have MONTHLY dues of $1000.00 or more to spread the costs over the owners not in foreclosure!
In addition to the HOA concerns, make sure that the townhouse is on FEE land (where YOU own the land), or you may find yourself looking at paying land-lease fees on top of th HOA dues!
Good Luck, and take care that you know all the costs before you commit to the property.