Indeed MorphOS license is a bit expensive for a low end computer like the Efika. Anyway, I don't regret to have bought a license though, but I am kind of addicted anyway ;-)
A viable solution to get a taste of it while spending as less as possible may be this: Get an Efika for 99, add the other necessary parts from #? (dumpster/attic/ebay) you end up at about 99 -250 total cost for the hardware. Then toy around with the MorphOS Demo, with Aros, with Linux and see what the Efika can and cannot do. If you feel you actually like MorphOS, but don't want to register for the Efika, you will soon have the chance to run it on a way more powerful Mac Mini (I expect 5 - 10 times the speed). After trying out on the Efika you will know if a Mini w/ MorphOS is worthwile for you or not.
99-250 for toying around - it's worth a thought. If you feel you don't like it at all, you can sell it off again with an expected loss of no more than 50.