Built the Foose pickup for an IPMS review. Used Pearl-Ex interference red over black, rolled the pans, and had to paint the bed because the decals disentegrated on me. Very nice kit with a 4 link rear and modern front suspension. I'll probably buy a couple just for the heck of it.
I don't keep track. If I need/want something, I buy it. I bought a '70 Road Runner for $15 and put Zimmerman wheels on it ($20), primer, paint, glue, etc. so maybe $40 or $45 in it? I would guess most are less than that.
Just about every kit has mirrors. Antennas? Use straight pins and cut off the head. After drilling a pilot hole and gluing the pin, put a couple drops of Micro Krystal Klear on the top, let dry, and paint.