Check your developer team. Have they done something like this?
Developing search engine crawler, with massive data, require experts in a wide range of topics, namely: database, coding, server, load balancing, etc. to name a few. Each of them could cost you six figure in salary per year.
Creating scripts that do what SEOMoz does is easy, but doing it in a matter that allows you to scale and could work flawlessly under heavy load is another thing.
I hate if this sounds as discouragement. Countless people give up their dreams every day because they listen to others who don't know what they talk about. I may not know you, your experience, etc., and I might be wrong... but from your questions, answers, etc. I sense you need more "real" information.
New projects always sound exciting, but please do your due diligence.