It really all depends - Often the cost of the repairs, even replacing such a simple component as the gear lever can quickly far exceed the (retail) value of the bike. That does not mean that it's not worth doing. You may spend $150 on tires, tubes cabling and a tune up, which is more than the bike is worth, but then you'd have a useable bike. A usable bike for $100 to $200 isn't that bad. I've also seen the cost of these "freebie" refurbish jobs quickly exceed the value of that caliber bike period. We've had junk mountain bikes roll into the shop and people walk away spending $300 to get it fixed, and be left with a junk mountain bike. It may function to the best of it's ability but it still not up to the purpose they are intending it. They'd be better off spending just a little more and get into a very bottom basement mountain bike brand new.