I picked up three mostly complete 8446 sets for 50-60 euros each 3 or 4 years ago... the big tires are unique, but they are also really really heavy. Ended up with a complete A and B model and a small pile of spares.
Right now I'm not really looking for any technic sets, I have just about every studless set and a few studded sets (such as the space shuttle).
I do regret not buying 2 41999s because I haven't been able to justify opening the one copy I did buy with the insane resale prices, but that doesn't count.