Sorry for the curtness in the first response, I honestly had you confused with a recent troll of a damn near identical name...
For $700, you can build a very good AR platform. There is a guy here, my young AR Padwan, named Junho who built a very good one for around $600 and he has a complete parts list in his thread
on the subject.
Now, if you are looking for a Mini 14 because you like the model, great. There is some stuff that you should know.
The Mini-14 is an op-rod driven action and on top of that, it has a skinny barrel. Both of those factors lead to less than great accuracy. Can you make it accurate? Sure. Out of the box will it hit Minute of Bad Guy all day long out to about 300 or so yards? Absolutely. Will it hold Minute of Angle out to 100 yards? I highly, HIGHLY doubt it....
Now, for $700, current price hike not withstanding, I could probably build you an AR platform that would shoot the living daylights out of the Mini-14.
Now, there are those that will immediately tell you that an SKS would be a better choice for a "battle/assault" style rifle and I would agree. The AK/SKS/Mini-14 are all Op Rod driven, which means they will run dirty and they will run cold and they will run when you pick them up...
Now, there are also people who will tell you an AR is maintenence heavy, it won't run dirty, it's a pain to take care of and that if will fail you when you need it most. Don't believe those people.
If you know how to take care of your weapon, which includes routine maintenence and cleaning, anything that "could" go wrong will be discovered long before it does go wrong. AND, in the unlikely event you find yourself at the range and your firing pin breaks ( never seen it happen ) or your extractor fails ( rarely if ever seen it actually happen ), or any of the other "horror" stories around the infamous Black Rifle happen to you, you will have the knowledge to fix it yourself instead of relying on someone else.