I was hoping that wasn't the answer. I remembered back in my old company that I use to work for they built their own one as it was too expensive to continue to subscribe to SEOMoz.
I guess there isn't any off the shelf sofrware that features similar functionality that SEOMoz offer I guess that are offering something unique which is why they can charge whatever price they like seeing as they have no competition.
The pro SEOmoz tools are well worth the money if you're doing client-based work and can factor the costs into your pricing strategy. I love the LDA tool and keyword difficulty tools in particular (although I wish they'd release an LDA API... it's such a ball ache doing the scores one by one!).
I think what you could use is a mixture of Market Samurai and the SEO Power Suite tools. I tend to use MS a lot during my initial keyword research and then SEO Power Suite for content audits / tech audits and SERPs tracking.
I think they'll set you back a few hundred dollars, but they're one-off fees rather than the monthly subscription.