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Without buying anything else, you could try the SB-25 on the D700. As gtmejon already said, the SB-800 has built in SU-4 mode, which will allow it to be triggered by whatever flash you happen to have on camera. Just tinker abit with both flashes manual output til you have what you want. I've used the SB-28 and SB-800 this way in the past.
You could always try a set of the cheap eBay radio triggers until funds allow something better. I think they run around $30 for a transmitter and 2 or 3 recievers.