Hey! I'm in N.C. as well. I wouldn't be surprised if I know of your local source.

Those large multifloral paphs can take years to bring to blooming size, and even then, it can be years between blooming even on large, established plants.

If the plant has 3 buds, it sounds to me like this is the first time it has bloomed, as I would expect to see 4-5 flowers on a mature, previously bloomed Lady Isabel. So, you're taking a chance on the plant -- it might be a blockbuster award quality plant or it could end up a total dud. Keep in mind though, that even if the flowers are very high quality, it's unlikely to be awardable with only 3 blooms.

The next thing to consider is, do you currently grow any other large multifloral paphs and have you been pretty successful with them? These guys take up a lot of space and can be a bit tricky, especially compared to the easier paphs like the Maudiae types and the sequential multiflorals. If you have little experience with the large multiflorals, then you may have to consider the fact that you're paying $90 to own this thing while it is in bloom, and you may never see it bloom again or it may be many, many years at the very least.

As long as you know what you're doing, it sounds like your growing conditions could work for the plant. These guys like lots of light, very good air flow, and warm temps. The caveat to that is that many people who grow roth hybrids mention that in order to induce the plants to bloom, they need to have a very wide shift in day/night temperatures, otherwise you end up with an expensive foliage plant.

In all honesty, without seeing the plant or knowing which roth and stonei cultivars were used in its breeding, it's hard to say if $90 is a good price or not. Certainly, I've seen blooming Lady Isabels for far more than $90, and I've seen them go for as little as $65. So, under the assumption that this thing has good parents from a reputable breeder, $90 is likely to be a fair price.

Personally, I wouldn't buy it, despite being a slipper guy, but that's because I have to avoid the big growers and I prefer things that bloom at least once a year in my conditions, and most of the multiflorals do not bloom that often when grown under fluorescent lights.