UPDATE 1/20/09
We got the estimate from the repair man.  
The low-ball (keep the existing boiler, clean, move) option is $3K.  No warranty on labor or parts.
The high-ball option is $4K (mew boiler to new location).  1-year warranty on labor & parts.
DBF and I are already scraping by as it is.  I'm praying and hoping that my homeowner's insurance will help defray the costs.  I've got a water damage rider, so am hoping that it's covered.
My mom keeps telling me stories about how awful she felt when their furnace went toes up when they were poor.  I reminded her that's the time her dad gave them a check to replace it.  He had written "antifreeze" in the memo line.  I told her that we don't have anyone who can give us the funds, and that we're in this on our own.  She told me to go with the more expensive route to extend the life of the system (which is only 9 years old and should last 30+).  I reminded her: no money - how will we pay for it?!?  She says I'll get tax credits.  Again... no money!!!  She stinks at being supportive.  Maybe I just stink at being consoled.
Please pray for me, send good vibes & thoughts, bestow me with karma, or whatever your belief system allows.  I'm at my breaking point.