Rapid start electronic T8 ballasts seem to be scarce even online. They definitely aren't a mass market item, and you won't find highly specialized items like that at a big box store.

You might try a good local electrical jobber, the kind of place that's open 8-5 M-F, maybe 8-12 Sat, and where you see electricians' vans parked out front.

For T8 lamps, rapid start has largely been supplanted by programmed rapid start and programmed start. These are even better for lamp life than rapid start. They're pretty widely available and reasonably priced these days, though less so than the ubiquitous instant start ballasts.

Programmed rapid start ballasts use the lamp's filaments to preheat the lamp before striking, just like a rapid start ballast. But while RS leaves the filaments powered up (using 1-2 watts continuously), the PRS ballast shuts them down after the lamp is struck. Thus a PRS ballast will prolong lamp life like a rapid start ballast, and will also conserve energy like an instant start ballast.

Where on-off cycling is frequent, a PRS ballast provide about 50% greater lamp life than a rapid start ballast, and about double the life compared to an instant-start ballast (20,000 - 30,000 starts). A PRS ballast will typically cost 50-100% more than an instant start ballast.

Programmed start ballasts are the gold standard for frequent starts, and for this reason are the ballasts of choice for motion-control switch operation. These ballasts use a microcontroller IC to tightly control filament temperature and lamp operating conditions. They deliver 4-5 times the lamp life of an instant start ballast (typically 40,000 - 50,000 starts).

PS ballasts used to be very expensive and hard to find, but (maybe because of the trend toward improved efficiency in public buildings) have become more common in the last few years. I found a GE Ultrastart online at 1000Bulbs.com for less than $25. That's only about 50% more than they get for a GE Ultramax instant start ballast. (FWIW, though there may be others, the Ultramax is the only ballast I've installed so far that has been totally silent.)

Link below. This is for information, not a recommendation - I've never bought anything from 1000Bulbs.com.

Here is a link that might be useful: GE PS ballast

Wow. Thanks so much for posting this!