The trick is all in choosing the right item. I'm not going to tell you which items I use, as I really don't want people interferring in the hopes of making a few silvers. You'll just have to do some searching through the market lists yourself.
One method I can suggest is to find those items which are only listed for 50%. Buy ALL of them listed on the market with your poor character, relist them for a lot, buy them with your rich character, then set everything back to 50%.
About the only way you can lose money this way is if someone notices what you're doing and lists a bunch of your chosen item under your price and then you accidentally buy his over-priced items instead of yours. This is the risk you take if you choose to transfer silvers with an item that is always available for sale at a store or the temple.
If you can't afford to buy all of the 50% priced items that are listed (and you can't find a different 50% item to use), a trick you may want to try is to liquidate the market items by buying what you can then selling them at the store to get your money back. Repeat until you can afford them all. This trick uses up clicks, risks thievery, and has the undesirable effect of draining potentially useful items from the market (thus driving up costs of related items), so you may want to plan ahead to avoid having to use it.
Sandy