When comparing slantback kit prices, you have to be careful to see how complete they are. Even if the main components are there, if you have to buy all those small parts extra, you´ll easily spend a few more thousand $.
I´d try to get as complete a kit as possible, even if it is more expensive at first sight. You need to learn those five or six pages from the parts TM by heart, so you can spot what is missing.
When I bought a slantback kit three years ago, I had the choice between a 99% complete, but rusty and more expensive one, and a nicer one that was missing some stuff even at first sight. Well, after spending a few hundred $ even on the missing 1%, I was glad I bought the complete one.
Parts are getting rare and more expensive.