Bangkok is a relatively cheap city. The hotels, even the really nice ones, aren’t all that expensive, especially not when compared to how much they cost in nearby countries.
The food is pretty cheap too, especially the street food for which Bangkok is renowned. The city has long been known as a shopper’s paradise. It’s where you can buy pretty much anything in volume. But as the country progresses economically, so do the standards and cost of living.
While you can certainly find good deals, you can also end up spending heftily if choose to do so.