$700 is a good price for a standard AR-15 type carbine. The AR-15 type platform, much like our beloved 'busas, is very customizable to the point of becoming very expensive very quickly. The problem (and blessing) with the AR-15 type, is that there are at least 10 different manufacturers of each and every part, and different configurations for many parts. You also get a lot of misinformation and myths about them (and firearms in general) from so many "experts".
I get the impression that you wish to give a civilian version of the M-4 to someone who is likely carrying an M-4 on foreign soil. If that is your goal, many companies offer M-4 clones in civilian versions. Most offer a decent product. There will be differences between them and a military M-4. All will have a lower reciever(the part actually considered to be the gun by the U.S. govt.) machined internally different so that the complete selective fire trigger mechanism does not fit. The barrel length will be different as well. The military M-4 has a 14.5 inch barrel length. Rifles must have a barrel length of at least 16 inches in order to not be classified as "Short Barreled Rifles". There are two main non SBR options here: barrels that are 16 inches or longer (usually 16.1 inches), and barrels that are 14.5/14.7 inches long with a permanently attached muzzle device to bring the legal length to 16 inches or slightly over.
I'd consider products by the following manufacturers (in no particular order):
Bushmaster Firearms- Overall they are very good. Sometimes they've been known to let cosmetic flaws go out to the public. They use a non standard rifling twist (1 turn in 9 inches vs. the military 1/7) on most of their barrels. They have been known in the past,when they were smaller, to substitute plastic in place of aluminum on some of the non vital parts likethe trigger guard, handguard retaining ring, and magazine release button.
CMMG- They are a relatively new company that has developed a good reputation for good quality. They specialize in custom barrels in various profiles.
Rock River Arms-They have a reputation for good quality. They have a background in target shooting, and it shows in both good and bad ways (it depends on your point of veiw). Their barrels are usually heavier profile under the handguards. They do not chrome line their barrels as a standard feature (target shooting bias). They attach the front sight base with straight pins rather than the military standard taper pins (no biggie, IMHO). They also use non-millitary standard rifling twist rates.
Colt- They are considered the gold standard by many. If resale value is your main concern, Colt is the one to go with. I'm not a fan for political reasons.
LMT- Considered to be almost as good as Colt by many Colt snobs. They attach the front sight base with straight pins rather than the military standard taper pins. I have no experience with them.
Stag Arms/CMT- They were parts subcontractors for larger manufacturers for many years. They have a good reputation. I have no experience with them.
DPMS- They are a company that produces budget oriented versions of the AR. The earlier products were not known to be of good quality, and their reputation suffers from it. They have improved their quality to the point that I consider them a viable alternative. Some of their parts like the furniture seems substandard, and would have to be changed. They do not chrome line their barrels as a standard feature. I do not know what they use for twist rate, as no chrome lining, for me at least, means I'd plan on changing the barrel any way.
There are others to consider. I'm tired of typing.
Avoid Hesse/Vulcan, and Century International. Some would add SGW/Olympic to the list to avoid.
Karl