My 2 cents...
Doopys Kit - Great overall resin cast blasters; great looking and fun to build. Sometimes these turn up for sale by 501st and/or FISD members.
Handmade PVC Pipe Kit - These can turn out really, really good if you have the time and skills required.
Hasbro Conversion - These are just plain fun to make and an easy blaster for trooping - plus it already has sound and lights.
Hyperfirm - This is a really, nice accurate light-weight blaster. However, I can't really see you mounting a sound board and/or lights to it.
Here's my Doopys, Hyperfirm and Hasbro Mods: