Call it the Big Boost and pretend it's magical. You get a BUNCH of stuff. Like 50K of all the goods, 7500 frags, 50 CC, 12 relics of every type and all that...for and amazing $29.99! But wait, order in the next 3 minutes and we'll double...that's right, double, all of it. 100K of all the goods, 15,000 spell fragments, 25 (more than double!) relics of each and every type, and as yet another bonus...one military boost building, not of one type, one of each! ELR, MMM and UUU, all of them just for spending $29.99 plus a small fee for shipping and handling. What a bargain! Sweet and magical! Make your City Great Again!
My opinion is, no matter how cheap or how large the boost, after it's used the game will then slow down again and ...oh, wait....you could just offer another "Bigger Boost!" Hmmm..you might be on to something here.
AJ