alt Hacker NewsOK, I'll bite. What are these primary sources? I've got hardback of Weinberg's Principals and Applications and of course MTW's Gravitation (a self demonstrating object), but I'd really recommend Caroll's Introduction for the coverage of cosmology.
Get into the notation and tensor formalism of raising and lowering operators, etc. It really helped make some of the results more clear to me, just as <bra/ket> helped with QM.
Or are you doing high end astronomy or building a back yard Wave detector? That would get truly expensive!
You have a point. And your pick is a good one, because it illustrates my point well. For most subjects, it is not just one book ( it will likely be several depending on how far you want to push it ), and I rarely see those falling below $100 range at this point. Heavens help you if you are looking for a specific edition. And the collection quickly adds up; wife is already making cracks about how we always need more books.
But yeah, thankfully on that front I am not at the experiment stage yet:D I think I need more money for that.. so far.. just a whole lot of books.