First of all, if you're looking to move in together, be prepared for money problems to comprise roughly eighty percent of all conflict in the relationship from now on. Maybe you and your gal will have more of a communist vibe than I and my lady did when we shacked up, but money is, if not the root of all evil, at least the root of all urges to punch your loved one in the mouth.
My advice would be to forestall that (inevitable) day as long as humanly possible by treating the issue like the Holocaust: don't mention it, then decades later deny that it ever happened. No, wait, not that. That's terrible. What you should actually do is let her know that you plan to give her all of the crystal palaces and gold-plated parasols she can eat one glorious day, but you just can't swing it at the moment.
The point I'm making incredibly clumsily is that you owe it to your girlfriend (and yourself) to be honest about the cash you have. Living within your means is an admirable trait--assuming you're not a jobless deadbeat--and something that any sane person will eventually come to respect in a partner.
She may be sad that she couldn't get her dream home of the moment, but in the long run that sting will fade, whereas the sting of finding out your live-in boyfriend has maxed out his credit cards and hung himself in the bathroom leaving you in a pile of debt fades somewhat less quickly.
Let her know that you understand how much the place meant to her, but be clear and firm when it comes to the money issue. Break down, honestly, exactly how broke your broke ass really is. If this is a serious, long-term thing you've got going on, it's about time to at least be knowledgeable when it comes to one anothers' financial situations.
Tell her that it's not that you don't think you two deserve a great place, or even that you won't find one soon; it's just a matter of being patient. If she can't understand that, PUNCH HER IN THE MOUTH.*
*The author does not condone punching your girlfriend in the mouth.
The first thing anyone should do when discussing moving in together is to create a tentative budget. You don't have to sign it in blood or anything, but it gives both of you a pretty good idea of what your range is. Also, write a list of things that the place must have (like central air conditioning, dishwasher, and storage space) and must not have (bugs, rodents, or a close proximity to a Hell mouth.)
Words of hilarious wisdom.
While I also do not condone punching one's girlfriend in the mouth, the rest of this was hilariously sound advice.
Just to be clear on that again, I also do not condone punching one's girlfriend in the mouth. LOL.
In my head that was a very nervous LOL. What have you been up to mr Jackson?
If you guys are ready to move in together, why is she unaware of you financial status. A year into any relationship I know what my boyfriend made. I knew what he could afford and what he couldn't. And just out of curiousity, why isn't it "what WE make? Do you not work or are you just sponging off him?
Whatever you do, do NOT get into a lease that you know you can't afford, most especially if you have any doubts that you guys will be able to fill out the complete time together (although that wasn't mentioned in your question).
Not only will you be perpetually stressed and squeezed for cash, the worst situation would be to wind up on your own in a place you have no hope of affording. It could wreck havoc on your credit score, as well as possibly being forced to share an overpriced apartment or house with someone you're no longer seeing because one or the other of you can't afford to leave.