I manage to do a lot of work with the RCMA palettes from CRC. I usually order the sample size which are $60 each (there are two different ones, so that's 36 shades for $120!). There are also full-size palettes available for a higher price, but i since there are quite a few colors that I never or almost never use, it's not reallly worth the investment for me. And you can always order individual colors/samples anyway. It's a cream foundation and lays on a little thick, so I usually use it with mixing medium to thin it out a bit.
When I first started out I used Studio Fix Fluid, which works great, but RCMA has proven to be a better investment (variety of shades, price, palette form, easy to store, etc.). I still have a few in my kit that I've found to be better for specific skintones.
I'm considering testing some MUFE HD Invisible Cover in my kit. I use it for myself and I absolutely love it. I think it would be fabulous for bridal clients, providing great coverage, a flawless finish and it turns out amazing on film. It's another large investment and not as ultra-portable as the RCMA palettes, but I'm very tempted!
When buying foundations for your kit, remember that even though you will need a variety of colors, it's not absolutely necessary to purchase every single shade out there! Get a mixing palette from Graftobian and get to work blending!
**Also, there are already some great threads here in this forum that address this and similar questions, so read on sista!