An offsite event doesn’t have to be expensive. Some are travel and hotel junkets but others are just meetings at some location that isn’t the office - it might even be the office of another company that lends you some space for a day or two. I’ve seen companies trade this favor back and forth. The only real requirement is that you get out of the ordinary space and routine of work so you can focus completely on the people you are with and what you’re talking about.