Personally... why stop at 1 link on page 1.... I don't feel I have a hold on page 1 unless I get 5-8 links on the first page with only 1-2 of them being ppc spots.
If you organically hit page one then you can get a real cheap ppc on the same search because the relevance is already so high... just be sensible about your ad text and landing page content so it is all aligned and you'll get $0.05 - $0.15 clicks while other are paying $0.50 - $1.00... But I guess it all depends on your profit margin and conversion rates as to wether it is worthwhile... in my space I'll buy every click I can get...
Find a niche like that and Google sends you one of these mini fridges for free!