I think Stephen Robinson summed it up quite well already, but I add my 150 ct anyway.
Genrally I haven't regreted a minute to register my 2 copies of MorpOS. So the price seems to be kind of okay to me. But I guess I am rather belonging to the small group of addicts with a walled filled (more or less that is!) with plenty of ???. Means I live in EUROland and even if I would be on welfare money (HartzIV) I probably could afford to register a copy if I really wanted it (would be hard though, I guess). But to rely on those crazy addicts seems not the best strategy to increase the user base...
There are two or three issues with the price.
1st: For those outside EUROland (and Switzeland or Norway or some ararbic emirates) 150 EUR is a lot of money. It is ot only the US. I guess for the felt value one US$ equals 1 EUR. Seems that a locens is subjectively 1.5 times as expensive in the US. But what about Poland for Example. Typical wages in Poland are about the same ammount of ZL (3332 ZL) that the typical working German gets in EURs (about 2570EUR) (US a bit less tthan 3000 US$). 4.2 ZL equal one EUR. So, subjectively in Poland a MorphOS key is 3.2 times more expensive. I think everone can calculate more examples and could endlessly philosophy about equity...
2nd: Psychology of sales. Everyone knows these #?9 prices. The trick is cheap and old and everyone knos this psycholgical trick. But still it works. A price of 149 would sell better than 150. Even these both prices are virtually equal - and everyone knows that. But still it works.
Also 129 would outclass 149. The best choice of course woud be the good old 99.- price tag. About 100 is a fixed sum. And 99 are still suggest a kind of a bargain. 99.- is a good price. It implies to be less than 100 (we all know it is 100 but we cannot escape the trick of the 99), You really need good reasons to cross the 100 barrier.
3rd: Well, the bound to one mascihine thing. I'd say it is okay, but it defintely doesn't make the registration and the high price more appealing. If the price gets dropped to 99.- I'd say keeping the maschine lock is okay.

I end this thoughts with my impression that the MorphOS-team is pretty aware of those issues. Well as informatic guys probably not so much about the psychology of prices (there is also the theory that an even price tag like 100.- gets percepted as fair and trusty, but reality shows that the 99.- works better on average). I hope they think about it. And even if I paid the full 150.- I'd say hooray the day the fee gets lowered, because I think it will yield more users.

One last thing: Even while my wallet is not empty I decided not to register all my three maschines capable of MorphOS, but only my Mini and Efika, my good old (over 7 yrs now!) Peg is kept on 1.4.5 (which also works very well!).