When considering an amp for ukulele, remember that there are guitar amps and acoustic guitar amps and I honestly have not seen an amplifier specifically for ukulele. An amplifier built for electric guitar will be voiced with a focus on the midrange, and will generally (not always!!) not sound very good with acoustic instruments (the ukulele being an acoustic instrument except maybe something solid body like a typical electric guitar).
Acoustic guitar amplifiers are wide range, some would even say the more expensive models are "hi fi". These will sound good with a ukulele as an acoustic instrument. I am sure that even among acoustic guitar amplifiers, some will sound better with a ukulele than some others. Since I have not tried my ukulele with a variety of amplifiers, the only thing I can say is that my AER Compact 60 sounds great with my ukulele, but then the AER Compact 60 is an expensive amplifier and so is my ukulele, with its factory installed LR Baggs active pickup system. My point is that everything in the signal chain is a variable and therefore each situation is different enough to warrant experimenting, rather than making a blanket statement that a particular amplifier will sound great with anything you plug into it. In the guitar community, people are always experimenting with changing this and that in search of "the sound". Over in the acoustic guitar forums, there is one setup that seems to be generally accepted as the golden standard, but complete, with preamp, amp, and speakers, and maybe an EQ, we are talking several thousand dollars. I do "play out" fairly frequently with solo fingerstyle guitar and feel that this warranted getting the AER amplifier, which is very small and powerful. <any performers use these, with one popular example being Tommy Emmanuel. These typicall sell for around $1,100, but I buy used and "horsetrade" to get something like this. There are certainly far less expensive amplifiers that will do a very good job too. It just takes some research and willingness to try before you buy, if possible. I think buying used is going to get you the best "bang for the buck" IF you have some safety measure if you run into problems with the purchase (i.e. at least a short warranty of 90 days or somethign along those lines).
As for specific recommendations of brands, I really don't know since I bought one amplifier and use it. I have read that Roland makes a series of acoustic guitar amplifiers that people seem satisfied with. I think these have already been mentoned in this thread. Another consideration might be a keyboard amplifier, since these are also wide range. Again, experimentation is the way to find out what is right for your particular needs. Though if a number of people all recommend the same amplifier, then it is a good bet it could work for you too.
Tony
