Hello Robin,

Thank you for writing in. I'll address your question in multiple steps.

1. Your composter is one I have never seen before. The claim that the compost requires no stirring or water is not something I am aware of. Composting is an aerobic process since the organisms that do the job of composting require air. They also require water. 

2. I do not know why the prices for composters vary so greatly, I am a Master Gardener Volunteer with the Ohio State University extension office and therefore cannot give any recommendations regarding price. 

3. The on the ground composters have many ventilation holes because air is a requirement for composting. The tumblers have fewer since the process of turning the drum introduces air. 

4. Since you have a smaller amount of waste, I would stick with a smaller composter.

5. Here is a link to composting basics. https://ohioline.osu.edu/factsheet/hyg-1189-99. I also like this link since it has a larger section on tumblers. https://www.nrdc.org/stories/composting-101#howto. The school garden,  at which I volunteer, has a tumbler that has a divider in the middle. It is ideal for smaller composting needs. You can add to one side only until you've reached a desired level. Then add the newer material to the other side while the older material composts.  

I hope this information is useful.

KIndly, Sabine