Thanks for trying it out. Literally the next feature on my list was to have little price animations when you placed something... but ran out of time! Given the time limits of the jam I kept much of the mechanics fairly simple. Sixty seconds of real time is 1 day in the game. Floors cost $2 and exhibits cost $20 each. Destroying an exhibit also costs (hey, labor isn't free!). :) Hiring staff either helps contribute to your visitor's happiness or to your income. For example without a chef you can't feed hungry guests... hungry guests are more likely to be unhappy. And without a clerk your gift shop (unseen) can't open. If your gift shop isn't open then guests can't buy souvenirs when they leave. One other "feature" if you didn't discover it, clicking an existing exhibit rotates it so you can place them facing how you want.
If this were to be taken from a jam entry to a full blow system I'd have more mini animations (purchases), mouse overs (tool tips, different prices), etc. I'd also like to see more visitor varieties, I had four different ones planned, more exhibits and background crowd noise that increases/decreases with the number of visitors. As you mentioned, for the jam I focused on the mechanics to ensure a solid experience of the core functionality. Nothing worse (to me) than a game that just doesn't work.