You can buy potted Lilies locally only. Reputable Lily sellers sell bulbs in spring and/or falls. For example, B&D still have some Lilies for sale. They send excellent bulbs (not sprouted of course) that will bloom for you this season, but blooming will be delayed.

The Lily Garden ships until mid-May. I would call them to see if they are still shipping. The are one of the best lily growers. They grow their own, rather than import and resell so you know they'll be fresh. That's more important when buying late in the season since you don't want bulbs that have been sitting around for several months.

They are a bit expensive, but if the roofers are paying for it (as they should) then that is OK. In fact, when you consider that they damaged established bulbs that you now have to start anew, its only fair that you should get larger better quality new bulbs to replace them.

I wouldn't worry so much if bulbs have sprouted as long as you are careful not to damage the sprout when you plant it they should be fine.

You can usually get potted oriental lilies pretty cheap at Lowe's, but your selection of type is limited. Local nurseries may also carry them. I'd call around.

Good Luck!
-Helen

Here is a link that might be useful: The Lily Garden - ordering info.