There is really no way to know what another advertiser is bidding. An Advertiser who has maintained the top page in ads for some time will have lower costs than someone starting off going for the same position.

This is because Adwords accounts in good standing appreciate over time. Keyword spy tools don't take this account and sometimes are very far off in their estimates.

However if you want to spy on their keywords, spyfu and keyword spy are good tools. Both have free versions that are sufficient for this.

Really though the best way to pick the right keywords is to go by relevance and quality score. Your quality score given to your keywords will be based on your landing page evaluation, and results similar advertisers have had with those keywords. The keywords you have the best quality score for, as with those you think are most relevant will be your best shot.

^^^ This post hits it right on the head. Can't get much clearer then that when it comes to getting started with PPC.