A church in our area has a plant sale every spring and has for the last 10 or so years, so I don't think it's illegal given these stipulations.

It is known that the bulbs are from a local grower and not a business.
That there is no profit except for the charity you are doing it for--I assume this is for some charity not for your own profit.

Make sure the bulbs are big enough to produce flowers next year or else let it be known that they will grow a plant but may not flower until the bulb gets big enough.

If it's a viable charity why not ask other gardening groups and even nurseries in your area to join in in donating extra bulbs. You could call it-- the(city name)gardeners bulb sale-for(charity). That lets people know the bulbs come from other gardeners and it's for charity.

Make sure each tuber has a viable eye. You mentioned the tubers had broken off the mother plants, quite often when this happens they will not grow because they don't have an eye. The eyes are usually showing where the tuber meets the stem. When dividing tubers make sure there is a eye on each tuber you are going to sell.

Annette

Unless those bulbs are patented I don't see any problems.