I also have PCOS and conceived my first child with metformin and clomid. I was on 1000mg of metformin (which causes a lot of people many stomach problems - apparently there's a "new" drug out there that is just as good as metformin, but better side effects - Glumetza). Clomid you have to be careful with, it's not good to take it for more than 6 mos., so it's good your Dr. will only do 3.
You might consider taking the metformin w/out the clomid for a couple mos. It's possible that will be enough..
I would call around for prices on clomid. I know Costco generally has good prices and from what I understand, you don't have to be a member.
What worked for me is getting the fertility test strips (I bought them on ebay). It was more accurate that temperature charting.
I conceived for the first time after two tries (but this resulted in a miscarriage) and the second time after one try (resulting in our daughter).
There is lots of information out there.... especially on the internet. soulcysters.com
One thing you may want to research and discuss with your dr. is whether or not to continue the metformin once you conceive. Everyone has different opinions on that.
Good luck!