I have now narrowed my main bows to two: one main and one back-up, both decent quality, but I have had my cheaper bows re-haired in the past and it makes a tremendous difference - even if the re-hair cost half of what the bow was worth!
I don't have a wide range of experience - I have only ever used Andrew McGill, on recommendation by many double bassists, and it cost me about £65 for a basic re-hair (I have had repairs and other jobs done) he's based in Oxfordshire. The cost reflects an excellent job and quality horse hair!
The little experience I have gained, I would say don't hesitate and get a re-hair!