I think I answered your question without being a smart ass. It does all depend on how much you spend. If you put cheap grips, cheap chain, cheap tires, cheap seat, slap a basic Predator engine on it, etc, etc, etc, then no it won't be worth $700. But if you buy a quality seat from Karen, put an amazing paint job on the frame, cool tires, build up the Predator engine with some good hop ups, add a chrome clutch guard, chrome fenders, etc, etc, etc then sure you could possibly get $700 for a bike like that. So to answer your question you aren't going to sell a bike you spent $200 on for $700 but you will most likely sell a bike you spent $1000 on for $700.