The One Ring is great as it (obviously) represents the site. The others are not so useful and have already been covered by GW, if you had say Harad that would be better (for me anyway).
When I had the recent TLA dice made I got them done in 2 colours to represent Good/Evil or Hero/Warrior dice rather than having different graphics. It costs no extra for multiple colour dice, but you will be forking out a lot of $$ if you have different symbols, you really need 500 of one dice type to make a good return.
I made 600 for TLA this year and could have sold more and 1000 a couple of years ago that just about sold, so please be careful on how many you order.
This year I put the graphic on the 6 as this seems to be the new standard on the latest games and the dice do seem to favour it. The old TLA dice seemed to roll nothing but TLA's when on the one
It might be an idea to look at
http://www.dice.co.uk you might get a better exchange rate, 500 dice 20p each +vat/tax - I can email their full price list if you like.
So, If I were you I'd go for 1 graphic and a couple of colours as members will probably want both and possibly sell more and go for 1 style only to start, it won't be any cheaper to have different designs made up to start with, guage the interest first before investing.
I'll take a set of OR dice, maybe 2; and if there was a race specific dice and depending on who it was for I'd possibly take 3 packs of one colour and 1 of another.
Good luck and give us a shout if you want to discuss any pro's and cons.
If you have several UK orders I could post them on for you, it may be cheaper that way. Including padded envelope: 62p for 1 set, 88p for 2 sets.