The lower-level pvp vendors are near the class trainers of each capital city. Note that these sell level 20 and 40 gear that is either blue or orange with blue mods but I don't think it has expertise on it. It's just stuff you can buy with comms. This is decent gear and might be the first chance to give a character implants and ear pieces, but it's just blue gear. The weapons vendors near the fleet pvp mission box sell weapons for various levels with expertise included.

I've picked up a lot of synthweaving schematics from Underworld missions....those and armormech. Did me no good since that character was cybertech. There are also probably a lot on the market since the folks finding the schematic don't need it as often. When you're making stuff to level, check for exceptional results with an augment slot. Sel those for more. Reverse engineer the other green gear you make until you get some patterns for blue stuff. Make blue bracers and belts, since those are harder to come by in custom (orange) versions. If you get a pattern to make orange stuff that only the opposite faction can use, sell it on the Hutt market on Nar Shadaa. If you make an exceptional blue item (with the augment slot), don't sell it cheap. Someone above spoke of reverse engineering stuff to get blue and purple patterns. The only purple pattern I ever got was reverse engineering blue things I made. That will get expensive. Also, if you happen to have another character with cybertech and/or artifice, you can add mods t the orange gear you make and put it on the market for a good bit more.