Alan Krutt bought tax-free bonds last month that were sold to build a retirement community in Boca Raton. Then he made an even bigger investment: He purchased a unit there.

The 81-year-old retiree from Boynton Beach faced stiff competition on both fronts. Octogenarians and high-yield bond investors alike clamored for a piece of the Sinai Residences of Boca Raton, which will feature rooftop gardens and a spa when it opens next year.