At this point be purposeful with your purchases... If Pandora ain't quite painted yet, you might be short on time. My advice is : Find out what's fun for you!??! Figure that out and let that be your guide taking into account time, cash and your gaming community...
1) if the community needs to be established still, then expand to other masters to have loaners and run demos... you already have Ophelia, which is mentioned as a great demo crew elsewhere in the forums -- so go ahead and get the Seamus box and run demos with them... Keep Pandora close by to show off the models and get people lured in with the fluff!
2) the game is meant competitively to be played faction-to-faction not master-to-master. You already have two of the 5 neverborn crews... If winning tourneys is important to you, round out what you already have with the appropriate blisters, then get other neverborn depending on your local community's meta-game.
3) If you're more fluff/fun driven, then get whatever you want. $50 for a crew box and blister means a small investment to get a totally different game experience!
Being a competitive-completist, I only have to get and learn to play 5 crews well and I'm done. I know if I start with a little of each faction, I'll always be looking to get all the models and I'm not going to get a second-mortgage on my house to do that considering wyrd's releasing 60+ models every year.
I love getting people involved and sharing the game, so I've got LJ, Colette, and Seamus for the family *COMPLETE until we have more kids*. I picked up Perdita to have 3 demo crews to intro the game to others *done*. I'm a completist and have chosen Neverborn as my faction; I have Pandora and Dreamer, so I've only aZ and Collodi in my sights as I'm not so keen on Lilith 'cause the crew is so horny.
In the big scheme of things, my story was:
*Loved Pandora's Crew's fluff, got into the game and committed to waving the Neverborn Flag!
*Needed Opponents Close to Home so next objective was to get Demo Crews: got Perdita for Son, Seamus for Daughter, and Colette for the Honey (and killed two birds with one stone: got instant home games and the kids just happened to like the fluff and models of Demo-Friendly crews; Of course, the wife went for Colette like 9 out of 10 wives have here on the forums)
*Then Nightmare LCB came out... GREAT neverborn model and crew! 'nuff said...;
*Needed a Melee-Centric Demo Crew (and got LJ) just to add different aspects to my demo games. Plus, son got to add Death Marshals to round out his crew somewhat.
Apart from getting more Neverborn, the only other thing I might need is a Magic-Centric demo crew (Raspy or Criid).
Just my two kanucks...