When I transferred, the gil limit was 100k (not sure about the limit on retainers, I didn't actually have more than 100k in total when I transferred )

A common solution is buying items that have a set value (like the allagan bronze/silver/etc. pieces) on the server you're on, transfer those along with you, and sell them again on the server you transferred to. Whether you can sell them quickly depends a bit on how many people are transferring off the server though.