I also found it difficult to start collecting Nothos, but there are some awesome folks here like Tyrone that have been able to get me started.
It is probably going to be better to start with fish instead of eggs, because you'll have plenty of opportunities to collect eggs to raise in the future, as oppose to one or two chances to hatch from eggs.
People say some are more difficult than others but there's a lot of different reasons that make a fish difficult and it all depends on what trips you up personally.
N. Rachovii are very popular and have a longer incubation time. That's probably the reason you just can't seem to find them all the time.
You gotta hunt on aquabid, and the BNL and always have an empty tank handy to take advantage.
Send me a PM, I probably have some eggs ready to hatch now that I don't really have room for.
This is probably the best site for species and pix.
https://wildnothos.wixsite.com/wildnothos