I've just finished installing a Fishman pickup and preamp in my Guitalele, for a total cost of R390 courtesy of eBay.
Full write up here, but some photos and comments:
The Fishman system comes pre-wired with moles connectors to join everything together- if your are comfortable doing the cutting work, the electronics side won't represent any kind of challenge. My only gripe is that the battery box doesn't show polarity for the 9V battery unless you squint at the labels on the PCB down at the end of the box, so I added a little label with + and - to the inside of the box. The top is fan-braced as you can see
I'm a little paranoid about cutting holes too big (you can always cut a small hole to size, but if you cut too big, well, ja) so I checked the template before taping it to the side of the instrument and cutting. Same procedure for the battery box
The bridge was pretty straightforward to drill for the pickup, a 2.5mm drill fitted the slot perfectly.
I've strung it up, tuning has settled and I'm pretty happy with it. There is an occasional buzz on some notes, I may need to treat it to a proper setup but I'm pretty happy with how it turned out