I just bought a cheap store brand one, and it has worked fine! The attachments I use most are the metal blades for chopping, plastic blades for mixing, and occasionally the slicer/grater. So I would definitely look for those attachments. The 'mayonnaise disk' for whipping things (like egg whites or cream) I don't use, because I find a whisk works better!
Likewise, mine has 7 speeds plus turbo/pulse, but I only ever use one speed and pulse so the rest were a waste of money.