don't hesitate to pay a bit more on your bass. as long as it is worth (sound, quality, aesthetics)
and $700 for a P bass is already a good deal as I have seen some of them them being sold for 1k.
I always believe in this
Good bass = makes you play it more = you get better faster.
and I always prefer getting 2nd hand basses, because usually brand new ones, you have to do a lot of setting up before it becomes comfortable for you. 2nd hand already comes with some cool mods(pick ups, preamps) from previous owners and action is already set for comfortable playing etc. and I believe that musical instruments get better with age hehe