Rota is an aftermarket wheel company that makes several cast aluminum wheels that will fit the Mirage. Some of Rota's wheels are kock-offs..or affectionately known on-line as "fake" wheels. In other words, they are copies of more expensive forged wheels.
Some reasons to consider Rota wheels
1. They have a good selection of styles in 4x100 bolt patterns
2. Their wheels are usually available in multiple colors...and some are available polished
3. A set of 4 is usually less than $450 shipped...so they're affordable
4. Many are available in 6.5 widths and offsets that will work on a Mirage
5. Many of their 15" wheels are surprisingly light...weighing 13 pounds or less (FYI: A 14x4.5 steel Mirage wheel weighs 13 pounds)
You won't find Rota wheels at the Tire Rack or Discount Tire. You normally have to buy these from sellers on eBay or Amazon.
Here are some examples of Rota wheels that are available in a 15x6.5" version with a 40mm offset. This is a fairly conservative 15" wheel size if you want to go bigger without running into clearance issues.
Here are the weights of these 15x6.5 wheels (in pounds):
Attack
13
Auto X
13
Circuit 10
13
Circuit 8
12
Grid
13
Group N
12.5
Subzero
12.9
Slipstream
12