Maria, my first thought was...a knife, but since you don't like the tears, you want to go a different direction. However, have you tried slicing/chopping onions with a candle burning near you? That helps to remove some of the chemical that causes the crying.
As for a good slicer, you can have good and you can have cheap, but not together. If you want good, but not necessarily cheap, purchase a mandoline. Just Google "purchase mandoline" and you will probably find plenty of places to buy them.
You should also check out kitchen stores in your area. Actually, I'd even look in the kitchenware section of Wal-Mart to see if they have an inexpensive version.
P.S. I know you are a "gadgetaholic," so be careful.