For keeping a razor in shave ready condition, all you probably would need is a Norton 4k/8k. Some people talk about barber's hones and strop pastes for this purpose as well. I think that they also work. If you by razors from ebay and would like to have more flexibility in the event of having to reset a bevel , I would buy this kit:

Amazon.com: Norton Waterstone Starter Kit: 220/1000 grit stone, 4000/8000 grit stone, SiC flattening stone: Home Improvement

When I bought my hones, this is what the experts recommended. I also bought a Chinese 12k finishing stone from Woodworking Plans & Tools | Fine Woodworking Project & Supplies at Woodcraft . It was about $20.

Al raz.