Generally, the rules in Avabur says that cross-trading is okay but discouraged.

The way I understand their rules is: you will be banned if:
(a) they determine that your account exists solely for cross-trading and nothing else;
(b) you trade out more than you use (i.e. you've used only 500 crystals on yourself so far, and you wired 600 to someone else)

So I was wondering if (b) counts the crystals that you bought from the crystal shop (either with cash or with in-game gold). Does it also count crystals that you purchased with fame points?

anything that goes out of your account is accountable, doesnt matter where you got it, but where it went. if gets out of your account, even if you donate to clan, which is an investment, it can get you in trouble. This is the most stupid rule ever conceived.

I understand that. But my question isn't about that per se. It's more about what gets counted as self-investment. My reason for this question I'm asking is because I'm wondering how Avabur's "50/50 Rule" (according to part (b) in my list) is satisfied.

To clarify what I mean, let's say I purchased 50 crystals with my Fame points and purchased 30 crystals with my in-game gold, and I already had 20 crystals to begin with (tradeable crystals). So now I have 100 crystals overall, but only 20 is tradeable. I invest 100 crystals in myself (in quest boost or whatever). Am I allowed to wire 100 crystals to someone else (eventually, once I get that much again)? Or would I only be allowed to wire 20 to someone else?

Don't know where you got the 50/50 thing from, I've only ever seen it stated that 2/3 of your belongings should stay in Avabur. I've done that so far by keeping gold/plat/crystals from the gold shop as things to invest with in-game (also attributing market sales from ingredients to my gold value and not buying crystals from the market with gold) while trading all acquired tradeable crystals through here for various D2 needs.

yes i think it counts, whenever you use crystals. doesnt matter if they are bought with fame, daily, or market

not sure so, just my opinion