Don't. Especially for books. Those are NPC seeded, therefore, the price remains constant. There's a sleepy little system 3J from Jita that carries 99% of them at seed price. The low/null skillbooks are almost always traps aimed at catching newbies in gatecamps, hence their lower price. Rigs aren't NPC seeded so their price can fluctuate, but honestly, I wouldn't buy those in low or null either given a choice. Large chance of getting ganked by someone looking to steal them.
There's a reason pirates banished to low and null have Jita alts. Trade in low and null just doesn't happen, far too likely to get blown to shit over your brand new shinies for anyone to do it.
Edited:
But of course. I like weapons that have range, don't have travel time, hit like a train, and don't require any cap to fire. Blasters have zero range, railguns don't hit for beans, missiles take forever to get there, and lasers take some serious cap. Autocannons and artillery? Perfection.
Well, that, and I like the shape of the Maelstrom and Hurricane, which are the two ships I spend my time in these days.
Im talking about leaving low to buy books and other stuff in Highsec. What is the best ship? Any tips and tricks about going about this?