I briefly saw Scott post in the thread you linked to that he's going with only new domes... how many of those are there?
Since Hasbro has made Build-a-Droids for R2s, R3s, R4s, R5s and R7s - the only "new" domes in the set are really the R6s, R8s and R9s - there are three each of those.
Color-wise, the problem is whether or not you care about the shade of color or mix of colors used. For example, the White w/Red Highlights R5 dome is pretty close to R5-D4, which they released using Build-a-Droid parts in the Vintage line. But the problem is that there's no "trunk"/"body" in the parts set that is comparable to R5-D4 since he has both red AND blue highlights - the White Body w/Red Highlights in the Disney parts set is unique in that way.
If you don't care about the shade of the color, you could probably skip making a droid similar to R2-D2 and also one similar to the White w/Green highlights R2 that came with the Queen Starship pack - those were both made using BAD parts, the only difference between them and what you'd get at Disney is the shade of the Blue and Green and the fact that the domes at Disney have holes at the top for the "hats". Continuing on the shade of color differences, the all-red Disney body parts are a lighter shade of red than the all red R2's body parts that came in that same Queen Starship pack, so again, all depends on whether or not you consider color shade a measure of "new"/"unique"-ness.
If you wanted to get new, unique droids, and keep the overall expense "down", I recommend building the following:
White Dome w/Purple Highlights, White w/Purple Highlights R2/3/4/5/6/9 Body & Legs, White Middle Leg
Black Dome w/Silver Highlights, Black R2/3/4/5/6/9 Body & Legs, Black Middle Leg
Blue Dome w/Silver Highlights, White w/Blue Highlights R7/8 Body & Legs, White Middle Leg
White Dome w/Yellow Highlights, White w/Yellow Highlights R7/8 Body & Legs, White Middle Leg
Red Dome w/Silver Highlights, Red R2/3/4/5/6/9 Body & Legs, Red Middle Leg
Green Dome w/Silver Highlights, Green R2/3/4/5/6/9 Body & Legs, Green Middle Leg
There are a total of six colors: Blue, Yellow, Red, Green, Purple, Black - you'd get at least one droid with each of those colors either the base color or the highlight color and you'd get 2 each of the three new domes - since you have an even number you could get 2-packs and the total cost would be $65.85 + tax.
Don't forget, if there are any color combinations you'd like to see, just let me know and I'd be happy to put those combinations together and snap some pics. I have my "open" set of 57 droids on a shelf that I can easily access, so it's no trouble to do so.
Pete, are you going to Disneyworld or Disneyland? We are flying into DW on 6/4...
We're going to Disneyworld - flying in on the 11th.
I've never seen anything new as far as parts are concerned.
Correct, the 25 domes, 10 R2 Trunks, 3 R7 Trunks, 10 Different Left Legs, 10 Different Right Legs and 5 Different Middle Legs are all the droid parts they've ever had (they also have the various "hats" but I'm not counting them). I think a couple of times the Disney merchandising folks have been asked if there are any plans to introduce new parts or the same parts we have now in new colors, the answer has been that they have no plans to do so.
The interesting thing is that the spot where the figure goes in the clamshell is big enough to accommodate a protocol droid, so I don't know if that's intentional or by accident - my thinking was that at some point they had planned on branching out to protocol droids as well, but have since decided against it.
My thinking was that since they had six different colors they could have at some point added purple and yellow base color parts, that way every color was used as the highlight color on white AND as the base color for each body part. The R3 with purple highlights on an all purple body would look pretty neat, same goes with the any of the domes with yellow highlights. I was also surprised, they never added a color like "pink" for girls to get into the action. I also wouldn't have minded an R2 dome with black highlights to put on an all-black & silver body, I think that would have looked pretty cool - it actually would have been neat if they had made it so you could make all-black imperial versions of each droid type available - as it stands now you can only do it with the R5 and R6 models.
The new All-Blue R2 droid that's part of the 60th Anniversary of Disneyland is technically "new" since from the pics I've seen there have been no parts in the BAD set so far that even come close to matching the color scheme they've given R2-D60.
Lastly, there's one more BAD, that even I don't have in my collection and it's the one that came in this set:
He's made using all of the same BAD part molds, but all of his parts have unique coloring. They had mountains of these when I was there back in January 2014, I'm not sure if they still do or not, I kinda wish they had made an option for getting the droid by itself, cause the colors on the fighter are hideous and I could care less about the Jedi Mickey. If I get to WDW and picking up R2-D60 is not possible (which I'm expecting will be the case either because he's not going to be available in WDW OR because he'll have been scarfed up in the previous Star Wars weekends) I'll probably grab one of these and have it shipped home.