Unfortunately, the IBM ones you can nowadays get seem to have deteriorated so much that it is more advisable to buy a new Unicomp. Or buy both and put the innerts of the Unicomp into the IBM case.
I disagree, most IBM Model Ms are in good shape, aside from perhaps the plastic rivets which can easily be addressed with a relatively simple bolt/screw mod. Even those that are worse off are not difficult to rescue and doing so is much cheaper than buying a Unicomp just for its inferior internals.
My first M was made in 1986, and I got it around 1993. I was at some guys place about something entirely else, though related to computers, and then I noticed he had a pile(!) of them laying around on the floor. It must have been 10 or 15 of them. Since I needed to replace my keyboard anyway, I took a look at them and immediately realized that this was the most awesome keyboard I had ever seen. I'd have bought at least two of them, but he would sell me only one. Perhaps he already knew what kind of treasure he had there.
I've never been able to get another one which was as good, and the more recently bought, the worse they were. However, that particular one had a problem with the detachable cable which was somehow lose in the connector at the keyboard. When it was slightly moved, the LEDs would all come on and the keyboard stopped working, and I had to reboot to get it working again. So that wasn't perfect, either.
Nowadays, it's a gamble when you buy one off ebay because you can't try them out first. And what other way is there to get one?
The last one I got has a broken Del key which you have to press ridiculously hard to make it register, and the right Ctrl key is sticky. I guess its barrel is worn out so much that the key would need a stabilizer to still work fine. I could probably fix the Del key by somehow replacing the spring if I had one, but what could I do about the sticky Ctrl key? I simply mapped Del to Ins, which I almost never use. Yet I need it for the movement when I play games, so I can't play any game that requires movement with that keyboard.
It's really not like the IBMs don't wear at all. The keys on the Unicomp are a lot stiffer to press and a lot tighter than the ones on the IBM. So even if you were to replace all the springs ---if you can somehow get them and figure out how to do that and if you have the time to do all that --- you can't replace the worn barrels. Before doing all that, what would speak against just swapping it all out with Unicomp internals? That probably takes only half an hour or so, and you are the closest to a new model M as you can get, unless you're really lucky or put out a lot of money when you find a NOS one (which still isn't as new as a new Unicomp, it'only hasn't been used).
The Unicomp internals may be inferior in that they use flimsy wiring --- which you could fix. Maybe the backplate is a bit thinner, just as the later IBMs aren't as nice as the more recently built ones. Perhaps you can also fix that by swapping the plate from the IBM to the Unicomp. The Unicomp internals work fine, and they aren't worn out to begin with, so they actually work much better than the worn out internals of the IBM . In that regard, the Unicomp has better quality than any IBM I've ever seen (which were all used ones, so I'm not saying that Unicomp internals are better or worse than new IBM interrnals).
As to prices, they have gone up since 1993 by a factor of 10+. Expect to pay at least EUR 75 for a model M. It can even be cheaper or same price to import one from the US despite the additional costs. That makes a new Unicomp about the same price as an IBM here --- if you can get one at all. Like someone said earlier, they'd be well advised to fix their website if they want customers, and/or sell them via ebay for the international shipping program they have. That's how I got my Unicomp.
Of course, the swap is only priceworthy when you already have the IBM. If you want a buckling spring keyboard for its function, buy new from Unicomp, unless you do have good reasons for wanting a "true" model M and are willing to put up with one that doesn't function as well as the Unicomp would.
Can you buy just the internals from Unicomp? I wouldn't even need the keycaps (but would probably buy them). Are there any problems with doing a swap like this?
Besides, currently I prefer buying keyboards new. I've used used ones for the last 25 years or so, and used keyboards are always somewhat filthy, no matter how much you clean them. (That's one of the reasons I would also buy key caps with the Unicomp internals.)
