200 - 300 $ would be my absolute limit & it would be a pen with an ultra crazy wet noodle nib - maybe one of these days (years, man, years!!)...
I consider any pen beyond, say, 80 bucks as expensive, because I got a few pens from the bay, which cost less then that: made from beautiful celluloid or HR, wonderful 18K nibs in excellent condition, some of which are terrific writers. So it`s difficult to justify spending more than that.
When I started getting into FP`s about 1,5 yrs ago, the third pen I bought is to this day my most expensive: Sailor Sapporo (Zoom), what with shipping & taxes .
My second expensive one was a golden Mabie, Todd & Bard. I had to have one of those because of it`s age & the terrific minimalist design
Since then, it went seriously downhill in terms of price, because I ignored the Usual Suspect Vintage Pens & - above all - only bought unrestored pens (anything with an inc sac I`ve learned to do).
Luckily I`ve no interest in modern pens (unfortunately the exception of this rule is the FC Intrinsic I`ve just ordered - it cost as much as the 19th Century Eyedropper )
In the end it`s all very relative (how much dough you have) but I say this much:
If you go vintage, even if you buy a restored one, you can get a high quality pen for under a hundred, which`ll give you a terrific writing experience.