Welcome!
Wow, I just finished writing the following and it is rediculously long. Sorry about that, feel free to skim.
[aside to Dick - you asked why I don't post often? It's because I always use up all the words in my computer by writing stuff like this and have to wait until a whole new batch of words hatches and grows large enough to harvest!]
Craigslist:
Here in N. California I'll see a month or two with only a few Mk V's, all in the price range you mentioned. However, those are the dry spells. More often there are at least 3-4, sometimes more, and the prices seem to average around $250-$350, at least those that are likely to sell within a month. Prices definitely drop below that but not much below $200 very often. As for 10er's, they seem to get listed for $125-$350, usually toward the lower end. There aren't as many but they are certainly not rare at all out here. I don't know if this helps, but at least it suggests there is hope if you've only watched for a few weeks or a month.
I got both my '83 and '52(?-missing serial#) Mk V's with planer, bandsaw and jigsaw for $250 off craigslist - the earlier one was thrown in for free ("broken" turned out to mean "needs belt"). That was a great deal but only because I have more time than money and enjoyed spending lots of time bringing them back to life. Likewise, I got my 10er just recently for $150 with the 10e* style jigsaw, speed changer, and lots of arbors, flexshaft, etc - most with original boxes. The freebee there was an old radial arm saw - from which I can salvage the motor, but that's probably it.
Now for the big gloat puncturing realities of the above: rjent is absolutely spot on in suggesting you'll probably spend more getting the individual parts vs getting a second one off craigslist. Although the two Mk V's had at least one of most things I easily spent well over twice the purchase price replacing missing things, upgrading some stuff, and getting good blades. Oh, another antigloat: my 10er is painted a crazy light blue - luckily my wife loves the color, so there is that at least. And
I think it looks nice and classic. Of course - I'm colorblind
Bearings...
As I recall, every single bearing on the two older machines and nearly all the bearings on the '83 were ready for replacement. Most were in true need, or long past. 60 years of sawdust against the bearing shield dries grease right out. In case you don't know... bearings should NOT spin freely when you spin them on the shaft by hand. That means they are dry. There are good videos on youtube on 10er bearing replacement and the sizes are listed in the sticky in the maintenance section on this forum.
OK, last bits - things that I learned that made a big difference:
Rust - try electrolytic rust removal. Seriously. Magic.
Wax!
GET DUST PROTECTION/COLLECTION. Real dust collection. Sooner rather than later. At minimum get a good mask - one you'll wear. Not as fun as buying and using other tools, but my lungs hurt for well over a month after I tried turning my second bowl without realizing the wood was incense cedar. I can't tell you how scary and uncomfortable that was.
I might suggest you start looking on Craigslist for another one. You could probably buy a second one for less money that what you are going to spend on separate parts ....