Calipers are necessary and useful for a lot of different reloading tasks, as well as non-reloading tasks. They don't have to be uber-expensive. I have used the same analog dial caliper I bought from Midway nearly 20 years ago.
If you're not chasing uber-precision or loading max loads, a digital scale is "good enough", but a beam scale is more accurate and more repeatable. I mainly use a digital scale, cross-referenced with a beam scale, these days.
You can start off wet tumbling with a cheap rock tumbler from Harbor Freight. Your volumes will be low, but I've found I can tumble a single range trip's brass in one or two tumbling sessions (minimum of 1hr tumble per batch). I do NOT use steel pins and find my brass gets plenty clean with just the brass, water, some detergent, and some Lemishine. If your load isn't particularly dirty, you can even skip a cleaning session or two. It depends on the load and gun though.
Chris