Housing prices are too high, many people can't afford to buy.
Tips
grammar
The 不起 complement works with many verbs beyond 买: 吃不起 (can't afford to eat), 住不起 (can't afford to live somewhere), 看不起 (to look down on - different meaning!). Note: 看不起 is an exception where 不起 means 'despise' rather than 'can't afford.'