So, there wasn't a pony after all.
I just bought a somewhat expensive education in things that can go wrong with buying an old house, and what to look for in 'bargain' houses.
1) It may seem like it'll be easier to deal with an owner directly, rather than going through a real estate agent. You'd be wrong. The agents bring with them a certain structure and discipline to the process which protects both sides of the transaction, even if they're mostly acting in the interests of the seller. In 'for sale by owner' transactions, you're playing without a net. I was lucky enough to have a co-worker who used to work in real estate law, who helped me along the way, and whose aid in preparation and drafting got me out of my trouble with most of my skin intact. Others might not be so lucky.
2) Houses are fiendishly complicated machines, and you really can't look them over in a single viewing. Every time I set foot in my aborted would-be purchase, I saw different things. Most of the time what I saw was unwelcome, which is why I waved off in the end.
3) Older houses are archaeological sites. They change with every new project their various owners performed, and few contractors have a proper respect for their predecessors' necessary structural elements. The house in question was build in the early fifties partially on an older house's fieldstone foundation; this was the start of the problem, most likely. Later contractors put a set of stairs into the basement, without proper support. Closets were built into rooms. The second floor bathroom's bathtub was moved back four-five feet from its original location, taking space from what used to be a walk-in closet. The house was expanded to the rear, twice. A roofed front porch was put in, without fully sealing the holes knocked in the brickwork.
4) The foundation is the spinal column of a house. If there's something wrong with that, the house is crippled. The house in question had at least four attempts to shore up the original failed foundation design over the course of fifty-some years. My sin in this transaction was in not noticing this initially. It was a complicated basement, and I should have thought through why it was that complicated.
5) Drainage is important. Even if you aren't in a flood area, if your gutters are ill-placed and you have bad slopes around your foundation, you've bought yourself a long-term heartache.
6) If it seems cheap for the square footage, there's probably a reason. If you can't see it, look harder.
7) A thorough housing inspection is the buyer's best insurance. Don't ask them to cut corners. Mine saved me years of misery.
8) Dryers need to be vented *outdoors*. Venting into your basement is a bad idea - it just introduces moisture directly into the foundation.
9) Closing costs are always more expensive than you think when you start house-shopping. Keep that money in reserve.
10) A draconian mortgage officer is also your friend. If they're tight with their money, they'll force you to be careful about your purchase. Also, they make for a dandy enforcer on your transaction. "They won't give me a mortgage because of this that and the other thing" is a great conversation-ender, or negotiation tool, if you've still got the sand for the purchase.
11) If you're not happy with the house as the closing starts to approach - get out. You're going to be living there, don't walk in the door hating it.
12) Be careful about tripping yourself up with the terms of your contract & deadlines. Give yourself enough time between the inspections & your mortgage application commitment date.
13) If you're not handy, why the hell would you buy yourself a fixer-upper? Old houses are almost always project houses; don't get yourself into more than you can handle.
So, I've got my deposit back, and I'm feeling free as a bird. I wish the owner the best of luck in dealing with his foundation fixes. He was very good about giving me my deposit back & terminating the contract. He's got a heck of a job on his hands, and I'm just glad it isn't in mine any more.