If you're really up for it, leave next week and you can score a flight for $179 RT, but those fares require overnights in Miami (MIA), I can think of worse places to spend some time stuck in. Flights departures vary and are selling out fast, but for the most part, if you depart before October and return in early November, you'll be able to find something that works for you.
As an example, searching on the AA website, I found seats departing DEN on Tuesday, October 30 and returning from SJO on Thursday, November 8, 2018.
If packing up in the next couple of weeks is too soon for you then take a gander at other options we have departing the Mile High City on the Denver (DEN) flight deals page.
Need a room in San Jose? Here's what's available from Hotelwatchdog on the sample dates.