Changeling1: First, I think you mean "Zuiko" lenses, not Suiko; that's not a criticism, just for clarity.
Second, can you be a bit more specific about the lenses? There were many versions of the 50mm lenses. Even if it's the common f1.8, there were at least 5 versions of that one, ranging from the F.ZUIKO "silvernose" to the latest "made in Japan" (aka miJ) designated lenses. Then there are the several iterations of the f1.4, and the f1.2.
Of the 28s, there were the f3.5, f2.8 and f2.0. Which flash? T-20? T-32?, etc. All these factors will influence the "value", some slightly, some greatly.
The value of the kit will depend on how recently the body has had a CLA, as well. I've gotten a very good OM-2 for as little as $55 with a beautiful brown leather case on oBoy, but I see bodies in excellent condition going for around $80-125.
The 50 won't fetch much unless it is a more desirable version such as the miJ, the f1.4 with SN > 1500000 or the f1.2. The latter is best sold separately, as it is fairly rare and can fetch a fair amount.
All the 28s will bring more, even the f3.5 could bring ~$40-60. The f2.8 might bring sligtly more, and the 2.0 the most due to the speed and relative rarity.
Of course, I'd give about $75 for the kit sight unseeen.