Since you cannot mail items between your own characters, the easiest way to get around this is getting a middleman.

Either get a good friend or a trusted individual from a linkshell or free company to meet you. Tranfer items, logout, login with alternate character and retrade the items.

I have a legacy character with tons of gil and shards so i basically had to relearn the game so i started a new character. I restarted as a lev 1 and joined FC and met a lot of good people.
-For me, my alt and main were logged out at the adventures guild in Uldah. Had a mate meet me, traded the items, switched chars., and had him retrade. There is an inherent risk to this, but just write down all u traded and offer a reward afterwords.

Hope this helps, happy playing.