This line of thinking is a major reason why the district system is implemented in Michigan and will likely expand elsewhere in coming seasons. Ramp Riot costs us an order of magnitude less to orchestrate than a Regional, yet attending teams consistently tell us that it is just as fun, and frequently moreso. In terms of experience per $, off season events are simply unbeatable.
That said, Regionals do offer some things that off seasons never will. The audio/visual production, the scale, the diversity of teams from around the globe, and the competitiveness (IRI doesn't count here, obviously
) make for an atmosphere that definitely adds something to the overall experience, in my opinion. For some students (and mentors), the "magic" of an official event (rather than playing in their own gymnasium) is an integral part of their takeaway from FIRST. Is that magic worth $5k+ per event? Depends on the team and their circumstances.
On a personal level, Regionals are a time for our team to focus on our goal of competing hard on the field - something that we can do 2-4 times per year, but definitely not 14 times (I'm burnt out enough after Championships). There's a reason Team 341 has won 5 Regionals in the past 4 years, but hasn't performed up to that level in the off-season.
Fortunately, you don't have to decide on Regionals vs. the offseason - you automatically get one Regional, and then can add a handful of conveniently timed and located offseasons at your convenience. Philly is an outstanding Regional; if money is tight, I wouldn't think twice about forgoing a second official event.
My one suggestion, however, would be to work towards a trip to Championships at least once per 4 years, so every full-time team member has the opportunity to experience the "Superbowl of Smarts" at some time during their tenure.