what is your budget and what is your style?
for straight up delay that is great on vocals i would say on the bottom you could get a deltalab delay for $50 that would do you nicely. also useful for crazy modulations. bigger numbers on the model mean bigger delay times. try the 1024 or so...
personally for vocals i like using tape delay sounding boxes. ibanez delays are great for this. the ad202 or the yamaha e1010. these are a bit more pricy at $125 or so.
for straight up no color no fun delays go with the above choices.
you might want to take a look at guitar pedals too, although some of these are pretty over priced. i have been using an "ibanez soundtank digital delay" for live stuff, and i got to tell you, it sounds pretty decent. i got it for free. see what is lying around your friends house. the nice thing about guitar pedal delays is that they tend to be designed to soften things up... which is nice. hard to knock out the original signal though, so you are stuck with your track getting lo-fied.
if you are really game, take a look out for tape delays. they run a bit more for one in good shape, starting at $100 for lo fi univox units all the way up to the grand daddy the space echo. working unit for about $399. but that space echo will never let you down, except for when it breaks, which should be fairly often.
