I have build a bunch. If you can find all real parts for a rolex sub that is all real for $2000-3000 I will build it for free as long as you get 2 sets of everything and I will pay the 2000-3000 for the other set.
The movements alone for most subs are over $1200 too around $2000. Last 16610 case I got that was real was beat up but came with papers and that was over $1000. A dial for a 16610 are cheap enough, at least the older ones. Your best bet to make a reasonable sub and it will cost you min $4000 is a early 16610. Realistically priced parts will be around....
Real case $1000-1500
Real movement working and serviced $1600-2100
Real 93150 with 580 or 501 end links $600 -$1000 used
Bezel and insert (now this is with a real crystal ring and parts) $900-1200 new. This is something you need! Trust me there is nothing out there that clicks like a real rolex. Well TC was getting dam close but he left. Plus it is a dive watch and I am a fan of a real crystal ring.
crystal=$150-320 (used-New)
Hands= good luck finding them. You have to find tritium rolex 3035 or 3135 sub hands. They can cost a lot. I don't even want too know but a guess will be over $400.
Dial= I have seen tritium dials for around $200 up to about $500
Crown and tube= (If didn't come with case) around $200 with gasket kit.
Now what does it cost too put it together? That depends on the condition of the parts and if cleaning movement or buffing case. Really can be an hour job or a 5 hour job with movement cleaning and so on. Hope this helps.
Take it from one that builds a lot of real Rolex for myself. Since starting this hobby I have build myself a real 16610, 16613LV, 16800, 116610LV, 116710LN, 16700 and a ton of ones that are real minus cases and some mostly real. It is NOT cost effective but fun as HELL. Locating the parts, slowly building the parts up then building them is amazing. When you are done you have a watch that is YOURS through and through. That is this hobby. So logic is thrown out the door.
Good luck and I hope this helps yah.