So I have this oil leak though, maybe one drip every 5-10 seconds at idle once oil is hot. I haven't had to add oil since the last change, 200 city miles, so it's not a terrible leak but I want to fix it. I realize I'll have to tear into the front of engine in order to really see where it's leaking from, but int. shaft bearing is the only place I can guess its really coming from...
Most likely it's coming from the IM seal, but it really could be any number of places. I wouldn't take stuff off until after I had thoroughly cleaned off the fuel & oil already covering everything. Degrease / pressure wash, then take it for a short test drive and see where newly-leaked oil shows up; should help you to zero in on it and verify that it is indeed the IM seal.
As for the pump, $350 for a rebuilt pump sounds a little on the questionably-inexpensive side (assuming that they refund you $150 for the core), and I don't know if I would order much of anything from PartsPlace anymore--word on the street is that the guy who started it and ran it for a long time recently sold it to his daughter, who's made a lot of changes, most for the worse. From looking at their catalogs they keep sending me, it kinda seems like she's trying for a higher profit margin, selling poorer quality parts for higher prices; they lost my business a couple years back. Now, in all fairness I don't know if they do their pump rebuilding in-house or farm it out, so it may still be good work that's a good value. But anyway, speculation aside, if your pump was serviceable before this happened, and you're just looking to get the pump working again and aren't necessarily looking for a fully rebuilt pump, there are more cost-effective options, if you're willing to take the plunge and take apart the pump to one degree or another.
To replace the main shaft bushing the entire pump needs to be disassembled. Now, granted, it looks very difficult and intimidating when you're doing it for the first time, but it's really not bad at all if you have or can make a few special tools, follow directions, and work methodically. If you can assemble a Lego kit then you can do basic work on an injection pump. There are excellent how-to threads, with step-by-step instructions all photographed that make it pretty straightforward, all things considered.
If you'd rather not have to tear down the pump entirely, another option would be to purchase a known-to-be-good, used pump with old rotted seals from one of the members of the forum and reseal it yourself. This would require a only a small amount of disassembly, and might not require any special tools at all, depending on which style pump you have. It's actually pretty easy to replace the main outer seals if you don't want to crack it open completely and do a 'proper' reseal. Genuine Bosch seal kits are available on ebay for under $25.