Boss has two different pedals PS-5 (Pitch Shifter) and HR-2 (Harmonist) which can do the following (if I remember correctly):
PS-5, in the fixed pitch mode, gives you a harmonized note which you can select the interval (up to 2 octives). Also available is a pedal mode - with an expression pedal (EV-5) plugged in, you can control your pitch shift so it acts like a whammy pedal.
HR-5 does not have the pedal pitch shift capability, but it can give you 2 different harmonized notes - all you do is select the key you are playing. For example in E minor, you can select one note above your key E (+minor 3rd) and one below (-fifth), you then get a chord-like output.
Of course, neither of these pedals sound as good as the Eventide. The Boss sampling circuits in these pedals have lower sampling rate, and the DSP chips are less sophisticated, therefore the reproduced notes are not as crisp and the pitch is not as precise as the eventide. However, you are talking about the difference between few hundred and few thousand dollars - you get what you pay for...
BTW, the HR-2 is discountinued but many can be found on auction sites.