Since bows are fragile, the rate of attrition is high, and therefore the price of old bows has nowhere to go but up. An authentic bow of established value can always be traded in against a bow of equal or greater value, minus any necessary repairs. In buying a bow, the only substitute for comprehensive knowledge is to deal with a reputable maker, dealer or expert. And condition is an important factor in determining price and salability. So if fine condition is not maintained, the value of your investment will decline.
Many factors can influence the performance of a bow, for better or worse.
So if you want to improve your performance, look for a bow which brings out the best tonal qualities of your instrument. For maximum strength and resistance, the evenness of the curve is crucial. If the stick is not centered over the hair, this can cause major loss of resistance. Balance can also be corrected and improved, giving better spiccato and overall ease of playing. A loose frog is dangerous, leading to frog damage.