Other than the max guild obviously, what are the best ways to get a crystal acorn? I am already hopping worlds for a crystal impling but it is an unreliable method and the only time I caught a crystal impling, I got some dragonstones.

Hefin agility with light familiar and enlightenment scrolls.

Actually there are 4 alternative ways (in addition to max guid) of obtaining one:

 

Crystal impling- this is the most common, if you buy the jars. But it's still likely worse than 1/100 chance.

Hefin agility- Likely extremely rare, up to 1/10k chance (~100 laps an hour).

Pickpocketing- Can be gotten by pickpocketing any of the elf workers in prif, although at extremely low rate(likely 1/100k~ 15M xp, 2k thieves an hour).

Slayer- killing cadarn and iowerth elves. This is also extremely low chance(worse than 1/10k, ~400 kills an hour). 

 

Overall, unless you have money to spend or are doing any of the other 3 activities anyway, it's not worth hunting for one. 

Thanks for the advice. If the rates are truly that high, then it isn't worth it.