Full map size

All you need is a 'supply' city to shop the market for you while you farm coins to pay for it all. I had the board only about half unlocked and storage at about 200, level in the 40's, when my supply city started buying up underpriced storage expansion materials and all land expansion materials, and selling them to friends only. I was able to buy all I needed in about a week, which is how long it took to earn the coin at about 80k/day.

My storage is now 250 (the final expansion costs 25ea item) and all land is unlocked, with roads laid out, tho not yet populated. I'm now steadily buying services to cover the extra area, while the supply city earns coin and expands its own storage and land at a level (8) that makes such purchases far more feasible given the current state of the GTHQ, which tho improved, still requires a lot of luck to find what you're looking for, but far less luck with only a handful of other items crowding out the extremely rare expansion items.