I found a great Armrest & Storage Console for my Mirage. I have included photo's and information about where I bought the console.
I had considered buying a factory Mitsubishi Armrest/Console. However, I didn't want to spend $140. I had seen some posts on this forum for an aftermarket Armrest/Console from Amazon. I found it for around $50. I then searched on Ebay and found a similar one. Here is one of the web links I found (Note: The price varies on EBay for this same item. Some sellers charge $30.00 shipping, so shop around for the best price with FREE shipping):
Storage Box Armrest Car Arm Rest Dual Layer For Mitsubishi Mirage 14 -18
It has some improvements over the one on Amazon and the price I found was $36.39 with free shipping from China. I could not resist, so I made the purchase. It didn't take very long to arrive. It looks great. They packaged it well, so it had no damage from shipping. It came with poor basic picture instructions (use the picture instructions on the Ebay listing instead) and about twelve screws. Assembly is easy and you only need four of the screws.
I quickly assembled the console and installed it into my car this morning. It just inserts into the cup holder and rests on the sides of the parking brake housing. There are no fasteners that mount it to the car. It doesn't need fasteners at all. It actually stays in place quite well. I like that you can quickly remove it anytime you want. I can't tell you enough about how great it looks and how functional it is. It has the capability to slide the whole storage box forward, just the top, or both. I find it is very comfortable for me to leave the back of storage box lined up with the back of the bottom mount. It has storage for documents on the top tray and storage for two pairs of sunglasses in the lower section. This is a great improvement for the Mirage and I highly recommend getting one. You won't be disappointed.