Guild Wars 2

Hey,
since the last patch I decided to play the fractals again.
My current fractal level is 20 and I want to get to a higher personal fractal level, but I am a bit afraid of 20+ fractals since I have 0 AR. I had no problems with the <20 fractals with 0 AR, but I think I need some AR for 20+ fractals.
To my question: How do I get AR the cheapest and fastest way? and how much AR I need for 20-30 fractals, 30-40 fractals and so on, to have a good survivability?

Greetings

I also had 0 AR until last night. I did have some tokens, though, and a ring dropped for me during level 13 fractals. I thought I could put a +5 AR into that but no dice, you have to infuse the ring, which takes a ton of RNG drops out of fractals. So I spent 75 tokens on an infusion from the golem vendor in the lab and put that in my ring for +5.

I asked my fractal running guildies how much is good, they said 5 is plenty up to 20, 10 is fine thereafter if one simply knows when to dodge. Note: I am on a defense-built guardian so I can take a heckuva lot of a beating compared to others, I’m there to support much more than to dps, but I only died 3 times on the level 13 run. The third time my zap to an almost dead cat golem was a microsecond slower than its pounding of me …