I think building them is fun. From time to time I build them for freinds or business associates. I've always been a "hands on" type person and ARs are very rewarding to me. The best thing about learning to build is that you can upgrade things later without waiting for a gunsmith to get to it or paying someone to do something that is pretty easy. I usually start my builds around a particular barrel I like, then gather the rest. Kits are a cost effective way to build a low cost rifle, but I tend to watch the EE for things I want and pounce on them when they arise for a good deal. Stay away from products that are famous for being out of poor quality, this can be very frustrating and take all of the fun out of your rifle.
At first, I built carry handle ARs, but I recommend starting with a flat top. YHM has some flip+up sights that are a great value and they are often found on the EE for good prices. The user "eguns" carries YHM at fair prices too. No I don't live near him, work for him, or have any vested interest in his company or YHM. See disclaimer in signature....
Tool investment is fairly minimal and you will have them to use later, so they keep paying for themselves and remain useful. You at least need and upper reciever action block, good vise, punches, rubber mallet, torque wrench, molt grease, and a good multi-tool. I have a DPMS, but it is terrible for tightening castle nuts. Maybe someone else will chime in about one that does that job better.
Just do it!
Show us your build when you get done