You are not going to like oem prices. I started a car fund, saved for 5 years to buy my e39 and used the left over money in the car fund to pay for the mtech front and rear bumpers.
I got F&R bumpers so my prices will probably not be that helpful. I would just use getbmwparts website to price the parts you are considering (from my parts list below) to give you an idea of parts prices. You can search multiple part number at once.
http://getbmwparts.com/
oem front bumpers with headlight washers retails for $683 and $546 is getbmw parts price. $655 and $524 for the one without headlight washers.
Paint and install was pretty expensive it came to $909. Remember that is F&R if you are only doing front it will be less. I got three different estimates and they were all in that ballpark. It seemed high to me, but I did went to three pretty reputable places. I think I asked another member and he told me he got his done for $600 or $700 for paint and install. I got mine done just before I left Raleigh this summer, you might be bale to find some better prices in your part of NC.
I think I would have saved $200 if I did the install myself, but I did not have workspace (apt) or enough time to do it myself. I actually got this done right before I moved back to NY from NC. If you have the time and workspace you might want to do the install yourself.
Ultimately its your money and you gotta ask yourself what you want to do with it. Also depends on how much of a perfectionist you are. Seems like most of the people on here and the other forum go with reps and are happy with the results. I am glad I went oem, but I am pretty picky, plus I had the money saved up already and the car did not need anything else at the time. Not to mention that was at the top of my mod list.
Here is list if you wanted to do everything oem for the front bumper
51-11-7-894-378 Front bumper headlight washer
or
51-11-2-498-507 Front bumper no headlight washer & no pdc
maybe
51-11-7-894-379 Front bumper headlight washer & pdc
51-71-2-694-899 Wheel liner/support Right (540/530/528/525)
51-71-2-694-832 Wheel liner/support Left (540/530/528/525)
51-71-7-892-296 F.L. metal bracket/support duct (530/528/525)
51-71-7-892-295 F.L. metal bracket/support duct (530/528/525)
51-11-2-494-193 Front Buffer Strip Left (Shadowline)
51-11-2-494-194 Front Buffer Strip Right (Shadowline)
51-11-7-890-013 Air Duct Left
51-11-7-890-014 Air Duct Right
51-11-2-695-761 Alternator Air Duct (528/525/530) Driver's Side
51-11-7-891-421 Fog Light Frame Left w/Alternator cut out(528/530)
51-11-2-496-284 Fog Light Frame Right (All)
63-17-7-894-017 Fog Lamp Left CLEAR LENS (540)
63-17-7-894-018 Fog Lamp Right CLEAR LENS (540) [you can get projector fogs for less, a lot of people liek them better especially if you want to do HID kit]
61-13-8-364-498 Plug For Fog Lamp
x2
51-11-8-191-149 Gasket
x2 (2125MM)
51-11-2-495-280 Black mesh grille w/ for T-grill and ducts
51-11-7-893-048 Web Center (commonly called T-Grill)
or
51-11-2-496-285 M5 mesh grille
or aftermarket sink drain style think someone might have black ones
http://www.umnitza.com/e39-m5-front-grill-with-stainless-brake-ducts-p-1326.html
http://www.modbargains.com/Aluminum-Grille-E39-M5.htm
51-11-2-693-539 Front Tow Flap may or may not come wit the front bumper
51-71-2-498-939 Front Air Duct
[prob can just reuse yours]
Hardware
Probably will end up with some leftovers
51-11-8-174-185 Expanding Rivet
x30 Schwarz
51-41-8-201-057 Axial Securing Clip
x10
51 71 8 176 503 clamp for euro porkchops
x22
51-71-8-218-852 screw plug (belly pan)
x3
51-71-8-218-323 screw plug (belly pan)
x9
51-71-8-229-003 expaning rivet (belly or pork)
x14
51-71-8-195-383 circlip (belly)
x14
07-12-9-925-731 Wheel liner body nuts
x8
07-11-9-901-299 Screw for wheel liner
x8