I guess that is up to the "real" collector's budget!
I consider myself a 'real' collector and my first one (with the clear feet) was too expensive to try to acquire another. There are just too many other things in yellow-green glass that catch my eye to try to double up. If you were asking about a particular piece of pressed pattern glass and had interest in the pattern, I would encourage you to find all the shapes (sugar, creamer, butter, compote, etc.). However, with blown art glass, it is not really considered a 'set', as each piece is crafted individually and no two are exactly alike.
Each collector decides their own parameter of what they want to add to their collection.
If you are going to go for all variations, I have also seen one with a red blush near the top of the posey vase. The area just above the foot was yellow vaseline, and the whole thing glowed, which meant that a small gather of cranberry was first made, then a larger gather of vaseline was added over the top. I think that one sold for about $175 USD on ebay about 4 months ago. I think my version with the clear feet sold for about $100 when I bought it.
just my 2 cents