Yes, there are several Boost buildings I would purchase with gold.
I think however, that they should be set up differently. Several should be released and all permanantly available in the store. They should cost around 100 gold so they are attainable to all over time. They should be costly to upgrade to Level 10 but each level should give out a "Quality 1% MOD", For example 1% IP gain during wars up to 10%, 1% faster stamina regeneration, 1% faster energy regeneration, perhaps even an income boosting mod. By making them permanantly available it means everyone can eventually buy them with their gold...(long term gold sales for GREE), and happy customers finding something NEW in an otherwise stale game of att/def stats.
Basically I am suggesting an expansion of the "Goodfella" status we all probably purchased sooo long ago. I threw in the suggestion of an Influence Mod, because well everybody wants an Influence gain.
*Perhaps they should be limited to 1...although being able to buy 2 of each would drive gold spending up, and over a long timeframe.