Hi. The "lenses" are really not lenses but rather macro filters.
Indeed the Raynox 250 is a nice choice. Raynox also has a set of three lenses (which I have noted in other posts of mine) which are quite nice as well. The three are the +6D, +12D and +24D.
I'd like to remind you that with every increase in diopter, you lose some significant depth of field. I didn't appreciate this statement until I tried to get a picture of a flat stamp with the +24. It is almost impossible to get a good pic from that filter, IMHO.
I mostly use the +6, and sometimes the +12. The build of the raynox is excellent, but the size is 36mm and hence you must add your zoom to bypass vignetting. Sometimes that adds to the picture, sometimes not. I am considering getting the 500d 58mm just for the size and +6.
my 2 cents