Two name servers necessary?

The requirement to run two nameservers comes from §4.1 of RFC 1034, and is indeed for redundancy.

There are numerous providers who will offer you very cheap "secondary DNS" service where they transfer the zone file from your primary server using AXFR. For example, in the UK we have a well-known provider who'll do secondary service for 50 domains for just £2.30 a month (just over 3 bucks).

This will give you the ability to manage and run the zone yourself, but still give you the resiliency you need.

The conventional wisdom is to have two nameservers for redundancy. Ideally, this keeps downstream name servers pointed in the right place even if, say, your colo is unreachable. If you are hosting these websites from your home, your weak link will probably be your connection or power, not the machines themselves (assuming you are using servers, and not repurposed desktops). Also, since you are hosting from your home, I'm assuming that high availability is not a requirement.

However, you need to make absolutely sure that you have a static IP address, as you will not be able to register a dynamic IP with the root servers. This means that, if your IP changes, they will be pointing everyone to the wrong place to look for the correct IP for your machines.

I have been using EveryDNS for my primary host. My domain is not setup this way, but they do offer secondary service for free. This would allow you to get a redundant nameserver on a different network and still setup BIND on your own.