You should contact an attorney to review the covenants of your unit and determine how best to proceed. Any unreasonable restriction upon alienation of the property is unlawful, but income restrictions may be upheld. It depends on the situation.
Alternatively, you may just have to wait for the right buyer. The problem is that lenders have put such restrictions on income ratios for approval of loans that low income buyers may not qualify for financing. Your unit may be worth more, but a low income buyer wouldn't qualify for the financing required to buy the unit.
Answered on Sep 20th, 2015 at 2:02 PM