Hello fellow reader,
I just started reading the same book myself. HOLY COW it's awesome!
As a web designer/developer, I want to expand my projects into the physical realm. I know almost NOTHING about the electronics or parts (other than playing with one of those hobby wire-to-spring boards as a kid), nor have ordered the hardware yet. I do know web related items, but have not gotten far enough into the book to really give helpful advise to you yet. I do however share your excitement!
I skipped over the PHP/Server part of the book. Initially I'm planning on using a test server at home. If you have an old computer sitting around, Ubuntu Linux has an auto web server install option when you boot from the DVD, quite handy for quick setups. You can quickly get a copy by going to a book store Linux magazine section seeking a "free" Ubuntu DVD (or you can spend hours downloading it for free). It may require more research though if you go that route as you need to set your internet modem to forward ports to your server, and do some other setup and understanding Linux stuff. I like this option because I can blow this stuff up and not make others mad. 
Not sure on cheap and ready SSH accessible hosting options at this time.
Briefly looking at sparkfun.com, it looks like most projects would go over $50 from what I can see, at least initially. Once you have some parts, it seems that you can take projects apart and build new ones, reusing parts.
Well I'm done with my mostly unhelpful rambling. Have fun! 