Researching with someone as a stopgap I am currently an undergrad student looking to research with one particular professor. On talking with his colleagues, it was suggested that I first get some research experience under my belt; the professor in question is a high level professor who is currently not looking for students and it would significantly help my cause when he opens up if I have research experience already.

There are other professors that I'm not particularly interested (interesting, but not amazingly interesting to me) in working with, but are open and would be willing to take me in currently. Is it ok to use these professors as experience builders on the premise that I would switch as soon as the professor I would like to work with opens up? If so, should I tell the stopgap professor that I intend on switching as soon as the other group opens up?

Just to be clear, I would put in the time required for the stopgap work - I would not just blow it off. I am just concerned about using someone as a stopgap and potentially leaving them high and dry if they expect me to be there for the next 3 years of undergrad.
If you came to me and said upfront that you wanted to get research experience and wanted to work with a variety of professors rather than making a full commitment to only one, I would try to find a way to accommodate you. 

Or at least I would let you know what my expectations are. But, in any case, we have an honest relationship. 

Now there would be no question of an ethical bind if you later decide to work with a more prestigious professor. 

But the honest relationship is very valuable given that the professors know one another and you don't want to get caught in a bind between two professors.