Yes The issue in this car is that you have tunned parts and therefore the price should be lower than those 300€.
Some of us want to think we have bidded for prototypes when they have only tunned parts
But a PB Alpha NIB for 300€? Well I doubt it but of course all depends where you get the item from. In a floamarket (do you name it so?) perhaps, but in ebay I strongly doubt it.
Another issue, is the price difference between different ebays. I must say that ebay.fr is not the cheapest one but of course if you want i.E. a Yankee or a Siccom it's the better place. But they cost often unaffordable prices for me, 500€ buy-it-now for a Magnum...
Last week I found a Landi in ebay with wrong description, in the wrong place and said to myself: "this is my chance"
A lot of people bidded, and of course I didn't get it
The final price is not depending on how rare is the car, but how sought after is it. Example: the Land Jump is well paid, but a Silver Fox is cheaper when it's more rare to find.