Re: MINI 14 580 vs basic AR 15 (accuracy&reliability)
You can find used ARs in the $6-700 range easily. Get your CA bullet button or whatever else is required to keep yourself legal and go with it. Watch the "For Sale" forum and you'll see them in there every now and then.
You can build one from scratch for pretty cheap too provided you go for stock components and buy used parts where possible. Your barrel and trigger is where it's at for accuracy, and a decent AR barrel isn't that much at all. You'll see some go very expensive on some builds, myself included, but it really isn't necessary when you're basically looking for a truck gun or range blaster.
All that being said, and the fact that you already have the Ruger, what use and performance are you looking to get out of it? Without a doubt you're going to lose money on the deal if you sell, and it all depends on what your goal is whether it will be worth it or not. Application is everything here.