With your options, the Superstone 1000, Chosera 5000, and Superstone 8000 would work well for your razors.

The 1K would be for setting the bevels.

The 5K would be for pre-polishing the edge. I only have experience with the Chosera 1K stone, but from what I hear the entire line of Chosera stones are VERY nice.

The 8K is for polishing the edge. A well polished edge gives you a nice smooth shave.

Once you are able to get nice and smooth shaves consistently off the1,5,8K, you can add finishing stones to the mix once funds are available. You may find that you don't need one too...the 8K will give you a good shave if you do your part all day, every day. The thing about shaving with a straight razor is that we all have our preferences & you have to experiment to find what you like. If you build a solid honing foundation on the three stones available to you, you could then experiment with different finishers to find what YOU like...but you must have that solid honing foundation.