Unless you want to deal in glass, the best way to feel comfortable on what to spend on a piece of glass to me is the following:
- Do I think this is a good quality piece of glass that I like and think is beautiful?
- Do I think the price asked is reasonable for the amount of appreciation I have for it?
- If the answer to both pieces is yes, then buy it.
To avoid the mistake of really overpaying, I limited what I spent on a single item initially until I'd learned more about what I really want to collect and what the prices of those pieces generally were. And as with any form of collecting, I guess, if it really makes me cry out "It must be mine!" and I can afford it easily, I just go for it, even if I don't know exactly for what price I'd be able to find it if I'd wait half a year or so. Since I still rarely buy anything over 50 euro, I don't mind if I 'overspend' by 5 or 10 euro, that's just the price of passion and collecting I guess...
After all, every computer I every bought would have been cheaper if I'd waited another few months in buying it, and every piece of really nice clothing is too expensive when it is part of the 'new collection'. It doesn't mean automatically I regret having bought those items at full price...
Astrid