Help with "L" Bracket choice & Possible additional Lens

I've been refining my tool kit preparing for portrait shooting. I'm not a "pro", but have some requests for shooting some portraits. I am seriously working towards a jump to full time. I'm trying to decide on a couple of things, getting an "L" bracket for my camera and perhaps just one more lens.
1. What would be a good L bracket? I know that RRS are about the best, but not in my budget right now. I'm looking at the Kirk. I can get a used one for $119, this is for a camera w/grip. I've also been looking at the Pro Media Gear. Anyone have any experience with the Pro Media Gear Grips? Any other third party L brackets that would be recommended, to work with my gripped 70D?

2. I've noticed that the 24-105 seems to be lens used by some "pros" for shooting portraits. I only have crop-sensors, so this is a consideration I'm aware of. Opinions of would it be a waste of funds given my current lenses?
Canon EF 100mm f/2.8 USM Macro
Sigma 17-50mm f/2.8 DC EX HSM
Sigma 70-200 f/2.8 APO EX DG OS
Sigma 150-600mm f/5-6.3 DG OS HSM

OOPS Just realized should have posted this in the gear forum.. Moderators please move this if not appropriate for this forum.

Given your lens lineup, it would be a waste of funds. The 17-50mm you have will give you a very similar field of view on your 70D that the 24-105 gives on a full frame camera. All of your current lenses you could use in place of it, the 17-50, 100, or 70-200 can shoot the range you are looking at, and have a larger aperture, so they can all be shot at f/4 or f/2.8 if you need it, and your 70-200 has OS if you need it.

Don't worry about what other people use. A professional uses what they have and are comfortable with- equipment is a tool, and using the tool you have and know well is always preferable to buying something new because that's what others use. Same thing with an L bracket. If you need one for a particular application or like the functionality they give you, then buy one. Don't buy one because you think professionals use them.

If you want to succeed in portrait shooting and want to make it a full time career, spend your time worrying about your business plan, CODB, marketing, overhead, insurance, contracts, and required income. Sit down with an accountant and realize the requirements in you city/county/federal level to run and operate a business. Come up with an income you are comfortable living with, and then find out how much revenue it will take to make that number after expenses and taxes.

Based on my own experience and POTN members recomendations 100L Macro is not a portrait lens. You could take toddlers portraits without flash with this lens under soft, ambient light. For the rest of human been this lens is too technical, too sharp.

You already have normal and tele zooms to get all portrait types covered. 17mm for groups indoor and 200mm for headshots in LF style.

I own several L-brackets, including the RRS for my 1D Mark IV. My favorite is by Pro Media Gear, as it comes in 2 pieces. So if I need to remove the side, I just loosen the screws on the bottom bracket and the side slides right out. I use this model on my gripped 5D Mark III and 6D, as well as my Nikon bodies.
http://www.promediagea​r.com/Canon_c_21.html

Whatever bracket you decide to get, try to stick with the same brand for any other brackets you may get in your setup. That will allow you to use quick release mounts since all of the brackets should be the same width.

If you get a screw type of mount then it doesn't really matter.

Those other ( insurance...) already been looking into that. I agree about the lens, main concern is in small areas. I'm not looking at things just because a pro uses.
For the L bracket, just wanting recommendations based on experience.

Thanks for the input on the L brackets. My setup uses ARCA style, not "quick" release as in lever. I can live without that for now.