There is no minimum, since experience at low resilience will help you learn how to play defensively, but I recommend shooting for 800+. It will be frustrating until you get to at least 600.
Here is a custom search of BoE PvP gear that you can use to jump-start your PvP set [wowhead] http://bit.ly/6ql9P
Also, check out the Wintergrasp Vendor, they have AWESOME ilvl 200 and 213 trinkets, belts, hoods, and boots available for purchase with WG marks. You can easily hit 1k resilience w/o spending a single arena point.
well i dont think i want to wait til i have 700-800 resil to start arena, i can at least get arena points before having 700-800 resil. Truth is i have already started arena and i've booted two rogues off my 2v2 team and now i got a new rogue and now my rating is shooting up cause he's much better then my last two partners. Only problem is he has 0 pvp gear and is naxed geared but at least he is pvp speced unlike one of my last rogue partnes who not only wasent pvp speced but was full of blues and green gear.