I was pretty disappointed to find out that the Vittoria Lite tubes are in fact not light... I guess they also have an ultralight or something as well but there is nothing light about their lite tubes.Vittoria makes good tubes too.
Do not get hung up on "25" as a necessary size for a tube. A tube labeled for a tire from 19mm-23mm will work just fine in a 25mm tire. You would NOT be compromising anything with a 19-23mm tube. That should broaden your tube selection.
I use the Continental Race 28 and stock up when they are on sale at Ribble - think the last order they were about $2.50 / tube.