Knights and resists

[Feanoir]

So after about 4 years of playing; the last two of which focused on my only toon to break lvl 20, I've finally hit 47....high enough to not get bumped out of the planes after a death. i'm gathering resist gear so that I might be somewhat appealing to a raiding guild. My question is at this point i have 0 plat to my name, i can always get more of course but I dont have 30k for a tranix hat or10k for an earring of essence. How much ac should i saccrifice for MR. I can crank it up to about 120 unbuffed but at that point my ac is down by about 100. I use a wurmy and sbs, already have imbued granite spauldors, those 13MR rings bracers of ro, and earrings of mag reflection. All my other slots end up trading a ton of ac for resist, and my base str is under 100 with resist gear. What should my ac/resist goals be in order to be the most use in a raid?