Different spirits go up and down in popularity, and there’s some serious savings to be had. Rum is also in a bit of a revival right now, but it’s mostly in young, spiced/flavoured rums. It’s hard to find any that you could call ‘old’ around here.
My recommendation for budget spirits: Brandy. It’s been unpopular for a while now, and you can pick up some shockingly good stuff on the cheap.