The Dance board was discontinued a while back due to licensing issues, hence the high price on EBay (if you can even find one at all). I had a go on the Techno card and wasn't very impressed (IMHO the loops were useless), but apparently the Dance card's very good if you can find one.

A much cheaper option is Roland's "Dance Kit" for the JV / XP range which can be freely downloaded from their web site and contains some very good patches.

Alternatively sample CDs can be good for dance music - if a proper sampler's too expensive then have you considered either a software sampler (Gigasampler?) or a suitable sound card such as the SB Live? Not as professional, but does the job!

Good luck...
Pete