Yep,pretty much,and you really dont want to skimp out just leaving a bunch of exposed wires everywhere and everything. You'd still have to wire up the controls,ect. A basic break down of what youd need with average prices:
Computer power supply $20,RGB to NTSC encoder,either jroks $80 or Yantons $30,3 RCA panel mount jacks$3,s-video panel mount $3, 2 DB15 game ports $2,quality plastic casing to house it all $20. 2 DB 15 game pad extension cords (used to wire up controllers) $14, 2 quality controllers will just depend price wise. You could use converted Sgea Genesis pads,or convert a couple of home system arcade sticks if you wanted. If you already have Neo-Geo AES sticks you wont need anything at all and wont have to buy the DB 15 game pad cords,as the Neo uses DB15.
The only thing that is left is to put it all together after wards,so if your good at cutting and soldering,you'll do fine,if not,find someone who can.