I'm in an extremely similar situation.
I got out of Uni 18 months ago and still have yet to find a 'proper' job. As such I'm 23, living at home with parents, and currently I'm afraid to say, am suffering a very boring life as a result with no disposable income etc.etc.
As such a relationship is just utterly impossible at this particular stage in my life. I do remember having a very decent prospect for one with a girl at work but decided to kind of blow her off just because I know full well I'm not leading a lifestyle that would be able to sustain it. Its horrible but I'd just be a complete let-down.
That isn't a low self-esteem issue or anything, but its just the reality that I'm living at home with parents and have very little money for that not to be a major issue. I'm afraid thats a deal breaker for most girls.