As said really get a good idea of what you want. Find friends with different ARs and see if they will let you give them a good session.
I went the full circle on the ARs in the last 4 years. I have come back to earth now. I have no real need to have optics on my AR greater than my mortgage payment.
I have since sold off all my "tactical" goodies. I retained 3 ARs out of the 2 I purchased and the 6 I built
1. My Stag model 2 flat top carbine-firts AR paid 849.00
2. My franknstienAR assembled with odd parts, free parts, swapped parts, used parts and I have a grand total of <500.00 into it runs fine. Its a carbine also
3. I have a AR lower and a tactical solutions 22cal upper on it.
Im also back to useing Irons except the 22 I have a 90s vintage propoint red dot on that.
Many late nights or early mornings on AR15.com should get you going. As for buying all the non FFL parts you need to try and find a source with that has most of what you want or shipping will eat up any saveings if you spread your parts out over different online vendors.
Find a few vendors and get on the specials mailing list if they have one. Gunkings.com is one of those vendors who at times has one night only sales ect ect
I also look for free shipping or discounted shipping.
Overstock.com has a good amount of add ball gun accesorries BUT be sure you know what the stuff goes for. Sometimes its not a deal on OS.com
In a nut shell I find my self wanting a standard A2 rifle.....I have a lower for that build but no $$$