Question: My web host is now charging $10 per month for an additional IP address?
Answer: Your web host may be running low on IPv4 addresses. If your web host is charging $10 per month for an IPv6 address than you should find a new web host as soon as possible. If its an IPv4 address than your web host may be trying to make some extra profit while citing a low count of IPv4 addresses as reason to charge so much.
IPv6 addresses and high costs
IPv6 are plentifully available and there are a lot of them available. If your web host is charging $10 per month for an IPv6 address than you should consider dumping your web host and finding a new one. If your web host is charging $10 per month for an IPv6 address than they are just making almost $10 per month in additional profit from you.
If your web host is charging $10 per month for an IPv4 address than they are taking an extreme measure. Charging $10 per month for additional IPv4 address can help deter customers that do not have a real need of an IPv4 address from requesting one. Your web host may be running low on their IPv4 addresses. They may have implemented this new policy to help cope with their low stockpile of IPv4 addresses.
By charging $10 per month for each additional IPv4 address may not result in much change. If existing customers have a lot of IPv4 addresses than your web host may in the future start demanding customers give up their extra IPv4 addresses back to the web host. The $10 per month fee is almost all pure profits for your web host. Your web host may decide to purchase additional blocks of IPv4 addresses from other businesses but the cost of $10 per month is an expensive fee from your web host and not from anyone else upstream.