Yes, I would definitivively buy the game now. Over here the basic game can be bought currently for 5 euro, and that is too cheap really
When you have bought the game you will have free access to all the areas (except those which are introduced in the expansions). It means after you go f2p you do not have to spen in-game "points" to buy access to those areas. Also, your account will become "Premium" after you stop playing (instead of f2p), which has quite a few perks compared to the totally free players (higher gold cap, more bags etc) plus 500 points which you can spend at for example removing the gold-cap or the limited bag-space.
So yes, I would definitvely buy the game before it goes f2p