You can honestly get away with using some of the cheapest stuff out there in terms of soaps, creams, etc. if you're not into the scents and the goal to find the absolute best. My first puck of soap was from wal-mart, in a mug from my great grandfather, and a vintage boar brush from his as well. Everything worked fine and I used only my Dovo blade for a few months.

Then I went wild and bought a Plisson brush, MWF Soap, more razors, hones, different scented creams and soaps (I think I'm up to about 10 different ones) and a new shaving bowl.

Using a straight can probably been insanely cheap in the long run if you let it be. There are just high startup costs. And it would be debatable as to whether you're better off sinking money into "quality" brushes, strops, and razors. A couple of my best shaves have been from $15 razors off of eBay that I honed myself. Meanwhile I have more than a few razors worth 20x (+) that amount.