The lodger next door gets by on about 30,000 yen a month.
Literal
Next [of-の] lodger [topic-は] month 30,000-yen [about-ぐらい] [with-で] lives.
下宿人 ('lodger, boarder') — a specific term for someone renting a room in a private home. 月 here acts as 'per month' without needing に (common for time periods in context). ぐらい ('about, around') marks the approximate amount. 暮らす ('to live, get by') takes で on the means/amount.