I know there are 3 different things in place to let you know that a fellow Galaxy member is the current top bidder on an item in the auction house.
1, The price is written in italics
2, when you click on the item and it brings up the item in a small dialog box, the price in that screen will be yellow/gold in color
3, If you click bid it gives a pop up saying that a galaxy member is the current top bidder and asks you to confirm your bid
Even with these measures in place it seems like some people are still outbidding their galaxy mates(which can be really annoying) and taking their stuff. So my proposal is to do one of 2 things, or both but really 1 would be sufficient
1, Anytime anyone is outbid by a member of their galaxy, a system message is generated on their galaxy message board(kinda like when someone uses a pillar crystal or donates ore to the pillar) with the players name(both the original bidder and the one that out bid them), the item in question, and the bid amounts
or
2, Anytime anyone is outbid by a member of their galaxy, a message is sent to both the player that got outbid(this could be just like the current mail message you get when ever you get outbid but could have the added extra of the galaxy member that placed the bid) and a message to the galaxy leader(something basic letting them know what happened, a who did it, who it was done to, and the item they are trying for)