I know this thread was started some time ago, but, I make most fo my Sim's money collecting metals and gems.
To really make it big, you need Carter's Display XL. (1,250)
Place an expensive metal ingot (value arround 600), not Supernovium or compendium, in the top left hand corner, then add another seven metal ingots. Anything will do so long as there are 5 different types. This is a good place to use those low value copper or lead bars. Total cost including 500 transfiguration fee should be around 1,400 to a maximum of 2000. Result will be a supernovium ingot worth approximately 7,000 to 8,000. A nice little earner.
Alternatively Place a medium-high value gem in the top left corner. Now add four more different gems. Finally add three gems of the same cut a one of your lower value gems.. It is vital here that you use 5 different gems and exactly 4 different cuts. This is a place to use up those low value emerald cuts of which you probably have plenty. Transfigure (cost 500) result is one4 un-cut soulpiece around 2500 to 3500 in value. Get it heart cut and it's 5 times it's original value or about 10 times your original invstment.
Transfigeration takes almost no Sim time! It's the collecting that eats up sim time. My preference for collection is France as metals are of high value, fequently found near the road side and the map is small enough that a sim can collect a lot in a short time, especially if they can jog between finds. There are some excellent locations for high value finds, but I'll leave you to find them. Remember that wherever you go in WA, the collectables do not start to appear until the day after your arrival on your first vist.
Revel in the money.