The LE went for ~$1300 on ebay when it came out. Check
www.djdeals.com and
www.agiprodj.com for good prices and service. Considering you were about to spend who knows on the KAB mods for 2 turntables, I don't think its that much.
I think the ttm56 is overkill for a begginer. An Allen and Heath Xone: 02 is almost half the price and will do just as well for sound quality and scratchability. I have one and its awesome. Or save yourself some more and get an Ecler Nuo 2 or 3, which has longer line faders for mixing and good crossfaders.
Rega vs stock 1200 arm: I agree the rega arm is more solid then the stock arm. The stock arm has a removable headshell however that I find useful. You could switch from DJ carts to any audiophile carts wiht only having to zero the tonearm and adjust VTA, whereas with the rega arm your stuck with 1 cartridge without having to remove, install and align a new cart. I've been told the stock rb250 is only a minor improvement, so I would definitely get mods done to the rega.
My advice again is to save your money and buy records! Get stock 1200s, play around with different carts and then see if money towards modded rega arms is really worth it.