Here’s a very rough rule: budget 10%-20% of your rent for the next year on design on the office.
20% usually can get you a pretty cool, if frugal, design. But if budget is tight, it may seem too much.
10% won’t get you all that much. But it will get you some nice enough touches to make the office cooler and more enjoyable.
It’s worth it. Why?
You want zero voluntary attrition. A cool office alone won’t do it. But making your office a bit aspirational can help.
It’s worth it for that, at least, once you are past the initial founders + a few early folks stage.