Many of those that say it's too expensive, probably haven't made the time commitment that is involved to seek out more economical flying. It can take ages to research and join a group or meet people to share your flying with- It's taken me 5 months! [Club-renting is a convenient and accessible way to fly but that justifies the premium]
For new/low hour private pilots [like me] that haven't really established a strong pilot network with which to share flying experiences, there are ways to get air-time: the 'Spare seats' thread, hanging around a flying club- empty seats/lonely pilots that don't use PPRuNe. Reading/discussing around anything that you think you need to improve on so that you accomplish more in the air. Lots of software out there these days too, its worth using things like RANT and FSX and the many apps that are available online.
I like the notion of having targets on specific flights- it can really stretch your time out usefully check-lists of tasks and challenges to work through. I keep a type of expanded log book/diary where I write up every thought and peculiarity of the flight.
When I was flying in the winter months, I could only manage about an hour/month!... In spite of it being with an expert instructor, it still took me about 5 hours of self-briefing and visualising to feel 'maybe I wont make myself look like a jackass in front of him this time'