Hello, I'm about to buy a vintage Parker Vacumatic (streamlined end cap) that the seller is advertising as an Extra-Fine Flexible nib pen. His writing sampler certainly looks the part, but I understand there are some Vac pens that can be a bit flexible without necessarily being a flexible nib. Even heard about one that acted as such because of cracks near the breather hole. Are there any special markings? This will be my first Vac and my first Flexible nib, what should I need to be aware of? Also, I will be paying about $88 for an unrestored but functional pen. Is this high/ low/ average? Thanks for your help!