It looks like the Esteem uses the 4X100 bolt pattern. You can swap wheels from Miata's, Neons, 200sx, the list goes on. If you go the the bottom of the page
here or to the 100 section
here it will give you an idea of a few places to start. not to mention you can hit ebay.
Remember, if you go with a wider 15" tire then the 5.5, you will most likely need to change your backspacing. I wasn't able to dig up what the stock backspacing is on the Esteem, but as long as you stay reletively narrow you should be ok. If you have more questions, call a local Les Schwab or other tire dealership and they should be able to point you in the right direction.