HR made this a major focus of the phone screen. If their salaries truly are "competitive", then why spend so much time asking candidates what range they are looking for before they even know what the job entails? It does not make sense. Standard tactics don't seem to work for deflecting the question. If you extremely interested in the job for whatever reason, then come up with a range that's based on glassdoor.com data and use that in a conversation with HR. If you don't have strong feelings about working for Illumina, then tell them that you would like t do some research before getting back to them and see what they do. Most likely they will screen you out at that point in which case you've saved yourself the wasted time in further interviewing with them.