You were lucky enough to get a tech who was honest enough to tell you that he does not know everything. Bring it back when someone is there that can tell you what needs to be replaced. Explain to them that you are broke, and will replace the parts yourself, but will bring it back to them for the alignment, if they will give you the courtesy of telling you which parts need to be replaced. Perhaps you will need to be willing to pay for the diagnoses with that being applied to the alignment. Do you best to work something out. A Pitman arm may cost approx $50 so you don't want to replace it if it is not needed.
Some chain stores, such as autozone have a tool loaner program, where you leave a deposit (enough to purchase the tool) and get it back provided you return the tool within a month. When I pulled my pitman arm, I used a pitman arm puller, AND a pickle fork (with a BFH) to get the darn thing off. They can be stubborn, and the use of air tools is helpful, but not essential.
Should you decide to tackle this project yourself, get yourself a chilton's, or a Haynes manual for your truck. And if you run into problems, let us know.