Well any of the generic brand brass cups and balls should work fine if you are not to serious about your cups. However I suggest picking up a set of cups and balls from
RNT2. They are pricey but in magic you often get what you pay for. Also if you go generic, I wouldn't bother with the combo chop cup. The gaffed cup is very top heavy, or is it bottom heavy? Also the cheaper ones tend to dent easily, so be careful about dropping them.
If you want a nice comprehensive dvd on the subject, I suggest Michael Ammar's work, or the dvd "Complete Course in Magic with Cups & Balls".
Silver
The RNT2 sets are really nice, but probably not something you want to get if you are just starting out. On the flip side, I have a "cheap" set (either Uday or MAK) and they work fine but are, as Silver said, easily dented. I think a good "in-between" set would be the Morrissey:
http://www.mjmmagic.com/store/morrissey-cups-and-balls-aluminum-by-morrissey-magic-p-2033.html
http://www.mjmmagic.com/store/chop-cups-and-balls-combo-aluminum-large-p-2040.html
The combo sets with a chop cup are great for starting out in that they allow you to do things that you couldn't do just starting off. But, as Silver said, the weight is different (that hasn't been a big deal for me) and the space inside the cup is smaller (which is a problem for me since some final loads don't fit as well in those cups). Also, the way the gimmick works requires you to keep track of where the chop cup and gimmicked ball are at all times in your routine. It's not hard to do if you plan your routine correctly, but it requires some thought. However, you eventually learn to accomplish the same effects as a chop cup merely by using slight of hand.
All that being said, my next set will probably be a "regular" set without a chop cup from RNT2 or Mikame.
I have the Eddy Ray Complete Course in Magic with Cups and Balls DVDs and those DVDs teach you what you need to know, but the Ammar set is probably better (but twice the price). There also is Street Cups DVD by Gazzo and 3 DVDs by L&L / World's Greatest Magic. I don't have any of those, but Gazzo is a master and the L&L DVDs are always good in that they have several magicians such as Frank Garcia, Dai Vernon and Alex Elmsley perform and explain their routines.
If you are just looking to learn the basics, there is a great routine in Mark Wilson's Complete Course in Magic. Every magician should have that book anyway. Again, if you are just learning the basics, the "cheap" cups and balls sets aren't bad.
The Stars of Magic book has (among other things) Dai Vernon's "Impromptu Cups and Balls" routine which doesn't require purchasing any cups or balls. I've actually done a routine with plastic cups purchased at Target and mini marshmallows (the final vanish tastes really good).