There's a lot that we don't know regarding the particulars, so I'll try to offer advice while offering the caveat that it could change if I knew more.
The OP seems concerned that the retainers he is being quoted keep becoming inflated. I'd be concerned about that as well. The inflation might be legitimate - as pdgpgpgpgp has intimated - or might not be, which is - I think - the OP's concern. Regardless, here's what you can do:
1. Ask your current lawyer to explain the difference in the retainers, and ask what exactly you can hope to accomplish once you hand over a retainer. Just be up front about it: "Hey, I don't have a lot of cash, but I want this done. Tell me what you need to get it done and let me know why, if I give you the money you ask for, you might not be able to get it done." The goal: make an informed decision about whether to stay with this attorney or not. You can't make that decision until you have information, like what exactly the retainer will be used for, what can expect to happen, etc.
2. Shop around for another attorney. I have a potential referral, if you're interested - just PM me.
Also, kudos to the OP for trying to do something right in the world. Too little of this going around nowadays, it seems.