Not sure where you got your prices from, but the suggested retail prices of the flash and the classic are the same at $99.95. The only differences between the two are that the flash is .5 oz lighter, the plastic parts are see-through, and the logo on the exterior changes colors when the water is boiling. Same boil time and efficiency. One thing I don't like is how the plastic warps and changes size when being used and can be difficult to get the lid secure after use (same on both).
I've seen two stores selling the classic for ~$65; it was also on sale at REI recently.
The Flash has integrated the piezo-electric starter into the burner. On my classic, the piezo-electric starter died after 5 years. I replaced the starter, but it seems to work fitfully. There is also a little folding 3-leg stand now that helps keep the cartridge a tad more stable, and lifts it off clod surfaces.
My advice - Get the classic. Yes, the piezo ignitor on it is nearly worthless. Mine only works when my hiking partner tries it as I'm saying "That's not gonna work; here's the stri..." However, most piezo ignitors are pretty unreliable, and you should always have a striker or some other ignition source anyway. It's also pretty obvious when it's boiling, so I don't think the indicator is worth paying for. The classic Jetboil is a great piece of equipment - very fuel efficient, lightweight, and compact.