The thing I found about Snap-On is not just that their stuff is the most rugged and lasts the best, it is usually the smallest in physical size. This is, in practice, the biggest difference between Snap-On and, say, Craftsman. Why should you care? Because Snap-On stuff let's you "get in there" in tight conditions. And those happen a lot! It's not unusual for Snap-On to be difference between being able to get the job done quickly and easily, or it being a female dog.
For this reason I would strongly prefer Snap-On sockets and extensions, especially for the 1/4 drive stuff. The Snap-On 1/4 stuff is so strong you can use it for things that other brands would be pushing you to 3/8 for. And again, why do you care? Access! Being able to easily get in tight spots.
I would take all the 40% off I could get, and contrary to a lot of others here, I would even take a reasonable amount of debt to do more of it. Saving 40% on tools and paying 12% or so interest is a great deal IF you only buy tools you will really need. Think sockets, universals, swivel sockets, extensions, ratchets, wrenches, ratchet box wrenches, screwdrivers, punch set. These are the things where Snap-On really makes a big difference.
Just my thoughts, good luck.