While the concept of a “bedding solution” might sound a little strange to most people, that is essentially what you need to be looking for when you are trying to find a bed for someone. It really does not matter whether you are looking to pick up a single bed, a double bed, a queen size bed, or a California king — you need to think in terms of what you (or the person who will be using the bed) are going to actually need. You need to let go of any kind of dogma about “what you should have” and focus on the needs that will have to be fulfilled by the bed in question.
If you need to have a small bed that can be moved around easily and will be outgrown in a few years time, you might as well get a single bed. If you are looking for something that will last for ten years (which is the recommended life span of most mattresses), then you might want to go with something that will be comfortable over the long haul. In the grand scheme of things, you want to actually be satisfied with the bed you get, instead of just “settling” for something, in order to move on to the next item on your to do list.
So, since you have a particular set of needs, you would be well served to write them all down well before you go into the bed stores (or start shopping online). While you may need a particular size, a particular consistency, and have a particular budget, remember that cheap, fast and good are never in the same room at the same time. You will have to compromise on one of those three facets, if you are going to actually walk out with a bed, instead of just your ideals.