I am having a pair of Ralph Lauren Purple Label Tuxedo pants taken from a 36 down to a 32/31" right now. My tailor said that is wouldn't be a problem at all, I'll keep you updated as I receive them back from the tailor.
as for suits, I am a 40$ drop 8 or drop 9. I always just plan on having the pants taken in. I may be shopping at the wrong places, but I have not found many quality suit makers that produce separates. Then again, I am usually bargain hunting