Hey, steel chainmail is worth more. Check it out for yourself.
Anyway yeah all those rock mugs pile up pretty fast.
I find that a loom, dyer and clothing shop can crank out some kick butt articles of clothing, even starting with simple pig tail and dimple cups. Start sewing cloth or silk images on them and you're good. to increase the volume of output, trade for bins of cloth, or farm rope reed as well. Once you get into the cavern, create a few looms and have one collect the webs and the other work on weaving. If you have just one loom, it can be a loooong time between weaving sessions, as the caverns are usually pretty far away from a workshop area... its a long way to walk to collect a single web.
Prepared meals, as someone suggested, can end up worth lots. Buy the expensive foods (50 dwarfbucks per item) on trade and try to cook with those.
I totally disagree that caravans tend to carry less. With my last trade with the dwarfs an exception, I end up spending 10k on booze from the elves. My fort has over 10,000 drinks available now. I don't think I'll need to use my still for a LONG time.
Also, if you have galena ore, smelt as much of it as you can, then set a metal crafter to stud items with lead. That in itself is not worth much, but his skill as a metal crafter will increase, so that you can effectively apply the silver and any other valuable ores you have.
The guy will stud anything nearby--furniture, chains, statues, flasks. Set the craftsdwarf shop next to a jeweler, and before too long you'll have a flask that costs $12k.