There is no free lunch, and like someone said, if you return because of buyer's remorse, it raises the operating cost of the store and eventually hurts the manufacturer (you think big boys like amazon would take the lost? It's going back to CM/or whatever the manufacturer)
Like many people here, I want to try all the different switches.
There are many ways to do it, if you have a local BM store, just go and try out the common switches.
For me, when I see a sales going on for a switch type (mx-green, mx-clear) that I can't find elsewhere, I buy it and resell it on classified if I don't like it for a 20-25% lost.
You can use the reverse method to find cheap keyboard from the classified section, and sell it if it's not your cup of tea.