I agree, make an offer and go as high as it is worth to you. I disagree about the extras, while it is true they don't add value if traded or wrecked they maybe worth something to you. If the mods are something you would do if purchased stock then they save you money and worth something to you. In the end if you want that bike and it is going to make you happy then it is worth as much as you are comfortable paying as long as you are not looking to make money or get your money back selling it.

I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!