I posted this on my guild forums and thought it may be helpful for other soon-to-be 50s...
With several people rolling alts lately and some about to hit 50 for the first time I thought I'd put together a short template for quick PvP gearing. If you plan to do a fair amount of PvP I HIGHLY recommend doing sub 50 PvP to bank up some comms. Ideally you'll have 3500 Ranked Warzone Comms(RWZC) and 2000 Warzone Comms(WZC) saved up by the time you hit 50. You can start buying RWZ at valor rank 40, so if you pvp as you level that would mean when you hit level 40 since valor is capped at your current level prior to 50.
When you hit 50, first buy two War Hero Implants and a BM mainhand weapon with your saved comms. The implants are generally the biggest bang for your buck since you don't need the BM piece for them first and the BM main hand will give you a large boost off the bat as well. Fill in EVERY remaining slot with recruit gear. Make sure you get the mission from the PvP terminal that grants you Recruit gear. Since you purchased a few pieces of BM and WH gear, you'll be better to get the token and sell it, then use that money to purchase the necessary recruit pieces. This will leave you with 650 RWZC and 50 WZC. At this point, you'll just save the 650 RWZC for a while and start focussing on BM pieces.
Your next purchase should be a pvp color crystal from the pvp items vendor. If you complete your pvp daily your first day at 50 you should be able to buy this. It's only 500(or 550 can't remember) WZC which you should get between the games you need to play for the daily and the reward. At this point, you will already have over 1000 Expertise in just your first day at 50! Here is an example of what a DPS shadow would look like after taking this path: http://swtor.askmrrobot.com/characte...6-0b7bd5ff9084
After that first day you'll want to start focussing on getting your BM pieces. I personally recommend buying the cheaper pieces first. This allows you to start boosting your stats quicker which will make you competitive more quickly. If you go this route you will purchase: Bracers>Belt>Boots>Gloves>Legs>Head>Chest>Offhand. Notice I skipped Earpiece and Relics. Those are best to keep as recruit until you can buy War Hero versions since the WH doesn't require BM to purchase. Buying the BM version is inefficient use of comms.
After you have a full BM set, buy your WH Earpiece and Relics and then start at the cheapest and work your way up again... Bracers>Belt>Boots>Gloves>Legs>Head>Chest>Offhand> Mainhand
After ALL of that you can start chasing BiS mods and enhancments from other classes War Hero gear