OK, an other viewpoint: a Rolleicord Vb in Ex condition will cost you € 500,- on ebay "Buy now".
A Rolleiflex 2.8F in good condition is for sale for € 1000,- and quite a few are under bidding right now.
On the other hand the FX is the latest model and new, so F versus XF is like used versus new.
The only thing I am not shure about is the type of battery used in the FX, if is mercury you are in a bit of trouble as they are no longer sold and you will need some extra chash to be able to use a diferent type of battery.
What I would do with plenty of money ? I realy don't know, probably get both together with a verry late 3.5F, but I got a 2.8F allready and love it. I got it for free as a write-off and restaured it myself.
What I would not go for: the T-model (never liked them) and the verry early models if you want to make pic's with one.
On the other hand, if you would run into a D or E model (have not seen any on ebay today) for around € 600,- in good working condition: by all means.
Some times waiting a bit does no harm to one pocket money-wise, on the other hand..... I would be tempted !
Peter