For me, it would depend on the stamp. Before I pop big money (for me $100+) for a stamp, I check prices (Ebay, Bidstart, auctions -- whatever is relevant) to get a feel for the price range. If the stamp is in an area I concentrate on and it is seldom offered for sale or is within the market price range, I would buy the expensive stamp.
If it is something I just want for my collection to fill a space, I would consider the lesser priced stamp "with character"

if it displayed acceptably. I would then be able to buy more stamps on my stamp budget. If my interests change, I can always upgrade later.
For me, stamp collecting is a hobby, not an investment. I don't expect my collection to ever realize more than a fraction of what I spent. Besides, if it came to the point where I had to liquidate my collection, I would need the stamps for a fire to keep me warm in my cardboard box underneath the overpass.

My collection is of much more value to me than what I could sell it for,
Dan
