This is what you do if there is no hopes of doing well in arena.

1. Make a arena team every week. (cost 200g for 5v5)
2. Do 10 games a week. (join and exit or play for practice... whatever)
3. Buy the Blue shoulders first. ( you will prob have 310 arena points after 1 week)
4. New week and new team get another 310 points or so.
5. Buy chest or legs.
6. New week and new team get another 310 points or so.
7. I doubt you can buy a 350 item so grab the gloves.
8. New week and new team get another 310 points or so.
9. Buy the other 350 item, legs or chest.
10. Keep doing new teams and bank your arena points.

You should have 4 of the blue items now.

During all this you should be running wintersgrasp everytime its up. Use the marks to buy the epic helm, boots, and trinket.
Try to buy 1 hateful gear a week to round out your set. Before you know it all the lvl 80 pvp gear will be in your slots. Run heroic vault and normal vault every week.

Now try to do arena seriously with lvl 80 pvp gear.