Yeah, they are crazy expensive, because they sell so few of them.
Unless she is absolutely stuck on the heal-toe shifter, try a set of footpeg stirrups from Kuryakyn. For a fraction of the price they provide the same heal support and ability to move your feet around as floorboards, without ruining the look of the bike, reducing cornering clearance, or costing an arm and a leg. YOu can easily adjust the angle of them also. I have a set on my Sporster and love them. You might even find a knock-off brand real cheap- I got a set of knock offs from V-twin, ISO-style pegs front and rear with stirrups on the front and matching shifter peg, for $75, but I do not know if they will fit a S50. But even the real Kury ones are like $120, way less than floorboards.
Might be worth a try, anyways. If they work out you saved hundreds on floorboards, and if they do not you can sell them on Ebal or put them on a different bike.
I looked into the Kuryakyn stirrups last year and almost bought them. Like DrBob said they could be an alternative to floorboards. Kuryakyn doesn't list adapters for the ISO pegs for the S50 but there are some that fit, I've seen pictures. If interested I have the info here somewhere.
Another option is the possibility that another Kuryakyn footpeg would be more comfortable, perhaps one bigger with more of a flat surface. Don't know myself, that's why I'm sitting here doing nothing. LOL. I think the stock pegs are kinda stinky myself.
Interesting. The previous catalog listed the 8820 and 8821 adapters for the front and rear of both the Intruder 1400 and 800. They fit, so I wonder why they changed the listing? Unless this is another example of the confusion caused by the dropping of the names and the swap to the S, C, M number designations for the models...
Anyway, 8820 is the adapter for the front, 8821 is the adapter for the back. Stirrups with large ISO pegs are about $110-120, less with regular ISO pegs. I had never considered them, but rode a friend's bike that had them and found them to be every bit as comfortable as the floorboards on my Electra Glide, but retaining the things I liked about pegs, so I bought a set for my Sporty. I had previously tried the ISO mini wings from Kury, but did not like them much.
I had checked the Suzuki part numbers for the stock footpegs and found them to be the same for the 1400 and S50/VS800 so it was my guess that the same Kury parts would fit both. As you said part numbers 8820 and 8821.
I've been considering a wider peg like the Widow or Zombie but the stirrups sound like they're worth a try. Once again DrBob thanks for the info.
I bought the large ISO pegs and the stirrups like in the photo DrBob posted. Just picked up my bike and darn, I like these. Not that I didn't think I would, but it usually takes time for me to adjust to new things. And I really like these right away. Great.