SEO (offpage optimization) of magento shops

We are a company from germany which runs several Magento- and one OsCommerce online-shops. We are selling toys, clothes and carnival-costumes. We are looking for a competent and trusty SEO-Partner for offpage-optimizing our shops to bring our GERMAN keywords on page one in the GERMAN google site. As already mentioned we are mainly interested in offpage-optimization, mainly because our sites are onpage-optimized to some extend already and changes that need to take place will be done by us. (Surely both parts cannot be separated ccompletely) So any suggestions to further optimize our püages onpage will be appreciated. Project Plan: - We want to give our partners several keywords packed together in "keyword-bundles" (each consisting of 10 keywords, some have 50). Some are very specific and some are more general/difficult. Also some are already ranked for our pages. - There is no target date, but keywords shall be on page one at the end of 2011 Payment details: - We are only able to pay on a result-oriented basis. This means that we will pay an single prepayment (per keyword-bundle) if 8 out of 10 keywords or 25 out of 50 keywords from a bundle are listed on google page one. - We are able to pay a single fixed payment (approx. 100$) which is taken into account with the bundle-payment We are choosing this payment model due to bad experiences with SEO-Partners in the past. If you are capable of doing this and interested in a long term partnership then please contact us.