I spent my entire $200 steam sale budget on used books.

I have also some good books that are not all 100% targeting pfSense it selfs, but it is constantly leading you
step by step to a  good stage of knowledge that will be 100% enough for building a home network and getting
enough knowledge to understand the most thinks.

Network-Fibel (written in German language)
Explains words and terms, what they are meaning, how they works, for what they will be used

Network Intrusion Detection 3rd edition Paperback (2002)
Shown you up all about TCP/IP packets and their meaning (nice to know for using wireshark, snort, suricata,..)

pfSense book 1
As shown in the link above, not really actual but relevant to pfSense and how it works and all his capabilities

pfSense book 2
Mastering pfSense, give you deeper knowledge about the configuration of your firewall

pfSense book 3
pfSense cookbook, lead you deeper in the system and its abilities to unleash the full potential of it

Squid book
Squid The beginners guide is telling how Squid works and what you can do for tuning it

Snort book
Snort IDS/IPS, how it works, what it does and for what it is

At last the Gold membership and the hangouts or group wise working on special themes would be
rounding up that knowledge and let you also being able to get the right things for your home network.

It depends also mostly on what you are interested and how much time and money you want to spend
for that action, but as today networking will be more and more reaching the latest corners of the whole
live of us all, and so it could be also seen more as normal. Also if you only will be using pfSense as a
firewall, without additional packets the three pfSense books will be enough for long cold winter evenings.

Thank you very much for the book selections!

Network-Fibel (written in German language)
Explains words and terms, what they are meaning, how they works, for what they will be used

Network Intrusion Detection 3rd edition Paperback (2002)
Shown you up all about TCP/IP packets and their meaning (nice to know for using wireshark, snort, suricata,..)

pfSense book 1
As shown in the link above, not really actual but relevant to pfSense and how it works and all his capabilities

pfSense book 2
Mastering pfSense, give you deeper knowledge about the configuration of your firewall

pfSense book 3
pfSense cookbook, lead you deeper in the system and its abilities to unleash the full potential of it

Squid book
Squid The beginners guide is telling how Squid works and what you can do for tuning it

Snort book
Snort IDS/IPS, how it works, what it does and for what it is

At last the Gold membership and the hangouts or group wise working on special themes would be
rounding up that knowledge and let you also being able to get the right things for your home network.

It depends also mostly on what you are interested and how much time and money you want to spend
for that action, but as today networking will be more and more reaching the latest corners of the whole
live of us all, and so it could be also seen more as normal. Also if you only will be using pfSense as a
firewall, without additional packets the three pfSense books will be enough for long cold winter evenings.

The book is the best resource I'd recommend. While the old out of print version Keljian linked does have a lot of relevant theory, that's also 7 years out of date at this point. I'd recommend the gold subscription and checking out the latest up-to-date version of it, and some of the hang out recordings on topics you're interested in. You'd get a lot more out of that for a lot less money as a home user.

Having traversed the same path, I highly recommend the pfsense guide here: https://www.amazon.com/pfSense-Definitive-Christopher-M-Buechler/dp/0979034280

While it is outdated in terms of the UI in the book, the concepts explained within are still very relevant

Cheers