There is no problem buying a factory made gun but often you will find there is something you don't like about it and you will end up making mods or having someone make them for you. Most often with Mil Spec guns, you will be less than happy with the trigger pull. Improving that most often requires you to spend upwards of $200 and more if you pay someone to install it.
Advice on here for you to build it is not for everyone. To build an AR, you will need some basic gunsmithing tools and that will boost the cost. Fine to do so if you also plan to build more ARs or work on other guns, etc. But for a one time AR pistol purchase and with your lack of interest in building one, you should proceed to a well stocked gun shop where you can handle a few different models and have a knowledgeable sales person give you some pointers about features and future potential. If they will allow it, do a trigger pull test and feel the differences. Also note the style of the AR. Do you want to have the iron sights or a flat top and you install your optic or both, etc.
I don't think you have gotten bad advice on here. There are simply a ton of choices and, if you go with a good manufacturer, you will probably be happy.
I was like you with my first AR and didn't want to build it and thought a well known manufacturer would keep me out of trouble. I bought a Smith & Wesson and was happy for a while. But I like doing my own work on guns, for the most part, and have quite a few tools. I have since built 5 ARs including one pistol. Much happier with all of them than with the S & W. I sold it.
