Don't worry winner, I understand completely where you're coming from and I think all these people attacking you and calling you immature are actually being morons. There's nothing wrong with you worrying about this and I actually think it shows a lot of maturity on your side.
Was in a similar situation last year, but from the other side. I was kinda sorta seeing someone who had just started working and earning a great salary and I was a student surviving on between R1000-R1500 a month, with my food, electricity, laundry and everything else coming out of that. We always had to do things that could fit my budget. He offered to pay for me for more expensive things on a few occasions but I always declined, because I would feel incredibly uncomfortable if he paid for my stuff. This meant I often couldn't share in everything he wanted to do. It eventually didn't work out because of this, so I understand completely where you're coming from and I think it's a very valid concern.
To all those telling him he's being materialistic and that if he really liked her he would take her in, have you considered how she would feel about that? She would have to become financially dependent on someone else and then become a drain on his resources. Don't you think this would likely make her very uncomfortable? That she might feel a bit like her pride has been diminished? And what happens if 6 months down the line the OP realises the relationship isn't going to work out and they break up? Must he then kick her out on the curb or let her stay with him and continue paying for her until she can find a place of her own again? Because that won't be uncomfortable at all...
It's very easy to sit in our armchairs and say OP must take her in and support her, but it's not that easy in reality.
OP, if you want things to get serious between you two, the best advice is to sit her down and talk to her about it. She might feel offended by it, but tell her how you feel about the situation and hear how she feels about it. It's important to get the issue out of the way early on, because it can ruin the relationship later on.