Do you mean they actually make AR's that are already put together?
If you want a perfecto rifle then the best way is to do your research, acumulate the parts, obtain proper tools ( a must, do not build it with pliers and crescent wrench) study available instructions so you do things once and correctly, do not buy the cheapest part ebay has to offer instead use reputable sellers--pay a little more and get quality.
In return you will have a special rifle you can have pride in....but be prepared to pay more than major brand entry level complete rifle offerings.
If you want a perfecto rifle then the best way is to do your research, acumulate the parts, obtain proper tools ( a must, do not build it with pliers and crescent wrench) study available instructions so you do things once and correctly, do not buy the cheapest part ebay has to offer instead use reputable sellers--pay a little more and get quality.
In return you will have a special rifle you can have pride in....but be prepared to pay more than major brand entry level complete rifle offerings.