Im not going to list everything but ill give it a go. Ill try and add my 2 cents for the ones I used personally.
1. Kaplan Blue book (great for laying down a foundation)
2. Destroyer (a must have for orgo/bio; great practice problems, some
of which end up on your exam verbatim!)
3. Crack Dat Pat (the best PAT prep out there)
4a. Topscore (great for testing yourself - I found the practice tests to
be very accurate compared to your actual DAT score)
4b. Achiever (never used it, heard it may be overkill)
5. Cliffs or Campbells's Bio - if you want a more thorough bio review
6. MCAT hyperlearning (made by princeton review - a nice complement
to kaplans blue book IMO)
These are what I would consider the "major players" as far as DAT prep. Surely there are other texts/sites/study guides that will be useful, but this is what most people use to study from what I have gathered. Your undergrad textbooks are also very useful, though not as focused towards the DAT (obviously). SDN is a great resource since many people will post and/or answer questions.
Ultimately, it is up to you to decide what you need to do to succeed. Ask yourself, can I study on a set schedule without classes? (if so, defintely dont pay for kaplan) Do I prefer learning from practice problems or reading? Would I rather really know the basics or see all the details and remember what I deem important? etc...
If money is an issue, I would suggest the following resources: Kaplan BB + Destroyer + Crack Dat Pat + Topscore. If you buy kaplan and destroyer used then pay for the others (which are online resources), youre probably looking at around $400. A great investment if you ask me. 🙂
Good luck.