$200 - KA Koncept speed sail. Only used once or twice when I was doing missions to Sandy Pt. Very fast and stable- perfect for a lighter rider not wanting to miss out on a nuking day at Lake George (or wherever). Extended foot to bring the boom opening a bit higher- makes it about 4.5m.

$200- KA Koncept 2006 7.5m. Comes with a 490 carbon mast. One of the super light weight Koncepts- higher aspect ratio. Probably work pretty well as a foil sail. Also was good for windsurfing.... Has a rip in the luff sleeve at the top of the boom opening. You could probably tape and glue it, or just be careful rigging (I used it for a while like this without an issue).

$280- Brand new Powerex 340 RDM. 85% prepreg carbon. Bought it as a candidate for a softer mast for speed sailing, but the wind stopped and I got too big to ever need a small speed sail... So its brand spankers waiting to get wet. Probably perfect for small wave sail for a foiler...