In a car, it will cost between $100 and $400 on average to have your bearings checked, repacked, or changed professionally (depending on your location and mechanic). Some servicers will provide these optionally during break tune-ups; others do not. Trailers tend to be cheaper to repack professionally (think $100-$200), but don’t underestimate the power of the upsells a mechanic might try to give you.
If you’re serious about cash, you can likely save a few bucks by repacking your bearings yourself. However, the tradeoff is a few hours of your time to learn and do the procedure, and a probable lack of experience in doing so. You stand to save a considerable amount of money if you do it right though – just make sure you know what you’re doing. Best case scenario: find someone who has done it before and ask them to show you how it’s done!
Whether you choose to use a professional or do it yourself, weigh the pros and cons of each option carefully before making your decision.