It's reasonable to be concerned about the fuel burn because avgas is so expensive these days. It's easy to spend £10k/year on avgas alone, if one goes places.
Unfortunately different people suggest different planes (their favourite ones obviously) without first asking the chap's mission profile - and he may not even be sure of it himself.
When I was looking to buy, c. 2001, I had all kinds of stuff suggested to me by people who I then thought knew what they were talking about. Most of it would have been useless for what I wanted...
For example a plane with a 500-600nm range would have been no good for what I wanted, and that rules out perhaps 90% of the options.
That's why the person needs to sit down and think hard about what kind of flying he/she wants to do. Most people that are to be found in the flight training environment haven't got a clue about this because they have never been past the crease in their map. This makes the learning curve quite steep.
On top of that one can get disingenous advice from a school which wants you to keep renting... Once you buy your own plane, they cut you out. No more fly-out invitations, because they can't make money off you, and you are pilfering people who would otherwise sit in the LHS with an instructor in the RHS
