If you don't have a flash meter, get a Polaris meter. It's about $180, and works with flash, ambient, and there is also a spot attachment available. I use one and it works great; according to my film it's accurate (I doubt it's 100% accurate; it reads a little hot according to some Polaroids I've taken), but it is plenty accurate for color neg/B&W film. You can adjust the reading, but I haven't messed with it. A used Minolta meter is about the same price.
A Flash meter and a handful of $30 "Neewer" flashes from eBay/Amazon is still cheaper than a Nikon CLS-compatible flash. Then all you need are stands, umbrellas, and a method of triggering: the Neewer flashes have built-in optical slave, so you can mount one on your hotshoe or use Pocket Wizards or "Cowboy Studio" triggers.
I use the flash meter to determine my ratios. If my key light is reading f/8 and my fill light is reading f/4, I know if I expose at f/8 I will have a properly exposed key light and a fill that is 2 stops under. This is a basic lighting ratio setup. Add a hair light behind the subject for a three-point light setup.
This works with film or digital. I set up my Neewer flashes on stands, triggered with Cowboy Studio wireless FM triggers, and metered with my Polaris meter. The Cowboy Studio triggers aren't perfect; I average one misfire on a roll of 36. I plan on investing in some Pocket Wizards when I get studio strobes, but for shoe-mounted flash the Cowboy Studio triggers are fine.
Sell your SB700's, get some manual flashes, a meter, and some method of triggering. For the times I want an automatic flash for my camera, I use a Vivitar 285HV.
I shoot with a Pentax LX or MX; thinking of getting an MZ-S for faster flash sync in the future. I may also switch (back) to Nikon for an F100.
The only thing I miss about using manual flashes over my Pentax dedicated flashes is the modeling light feature of the Pentax.